Std basic ostream link error

std basic ostream link error

Questions Related To: macos, c++, xcode, std, linker-errors "std::ostream& std::ostream::_M_insert(void const*)". In case of linker errors which I cannot resolve, I usually use a tool called Depends.exe which identifies the library it cannot find. I had the exact same error message. I used to forward declare std::ostream in the hpp file by using #include then #include Related Videos C++ Linker Errors

Std basic ostream link error - theme

[Solved]-Why M::operator<< causes a link error instead of std::cout::operator<<-C++

The answer is - because has non template version for which is selected:

With such version also in your program:

your code compile w/o problems.

More background - your real type is - so compiler best guess was:

As you can see - reference is required in this version - more or less this means shall have an address - it cannot be true optimized-out const.

You might also give this variable an address by defining it - like any other static variable of a class:


The overload resulation is really tough subject - most of the details are here, with template as new complication level - read here.

Just to make things a little simpler - let investigate much simpler form:

  1. Fail to link - because is selected - it requires "address"

Code:

  1. All fine - converted to - not "address" needed:

Code:

  1. Compiles fine - because non-template version is selected - non-template versions are always matched as first choice (this is more or less the std::ostream case - and my advice how to change your "stream" class):

Code:

  1. Fails to link - because we have only template version - and it requires "address" - this equivalent to your version from question:

Code:

std::basic_ostream

State functions

good

checks if no error has occurred i.e. I/O operations are available
(public member function of )[edit]

eof

checks if end-of-file has been reached
(public member function of )[edit]

fail

checks if an error has occurred
(public member function of )[edit]

bad

checks if a non-recoverable error has occurred
(public member function of )[edit]

operator!

checks if an error has occurred (synonym of fail())
(public member function of )[edit] checks if no error has occurred (synonym of !fail())
(public member function of )[edit]

rdstate

returns state flags
(public member function of )[edit]

setstate

sets state flags
(public member function of )[edit]

clear

modifies state flags
(public member function of )[edit]
Formatting

copyfmt

copies formatting information
(public member function of )[edit]

fill

manages the fill character
(public member function of )[edit]
Miscellaneous

exceptions

manages exception mask
(public member function of )[edit]

imbue

sets the locale
(public member function of )[edit]

rdbuf

manages associated stream buffer
(public member function of )[edit]

tie

manages tied stream
(public member function of )[edit]

narrow

narrows characters
(public member function of )[edit]

widen

widens characters
(public member function of )[edit]

std::ostream::write

public member function

<ostream> <iostream>

ostream& write (const char* s, streamsize n);

Write block of data

Inserts the first characters of the array pointed by into the stream.

This function simply copies a block of data, without checking its contents: The array may contain null characters, which are also copied without stopping the copying process.

Internally, the function accesses the output sequence by first constructing a object.
Then (if ), it inserts character into its associated stream buffer object as if calling its member function until characters have been written or until an insertion fails (in this case it sets the flag).
Finally, it destroys the object before returning.

Internally, the function accesses the output sequence by first constructing a object.
Then (if ), it inserts character into its associated stream buffer object as if calling its member functions or until characters have been written or until an insertion fails (in this case it sets the flag).
Finally, it destroys the object before returning.


Parameters

s
Pointer to an array of at least characters.
n
Number of characters to insert.
Integer value of type streamsize representing the size in characters of the block of data to write.
is a signed integral type.

Return Value

The object ().

Errors are signaled by modifying the internal state flags:
flagerror
-
May be set if the construction of failed.
Either an insertion on the stream failed, or some other error happened (such as when this function catches an exception thrown by an internal operation).
When set, the integrity of the stream may have been affected.
Multiple flags may be set by a single operation.

If the operation sets an internal state flag that was registered with member , the function throws an exception of member type .

Example



This example copies a file into memory and then writes its content to a new file.

Data races

Access up to characters pointed by .
Modifies the stream object.
Concurrent access to the same stream object may cause data races, except for the standard stream objects (, , ) when these are synchronized with stdio (in this case, no data races are initiated, although no guarantees are given on the order in which characters from multiple threads are inserted).

Exception safety

Basic guarantee: if an exception is thrown, the object is in a valid state.
It throws an exception of member type if the resulting error state flag is not and member was set to throw for that state.
Any exception thrown by an internal operation is caught and handled by the function, setting . If was set on the last call to , the function rethrows the caught exception.

See also

ostream::put
Put character (public member function)
ostream::operator<<
Insert formatted output (public member function)
istream::read
Read block of data (public member function)

question

I have this error in visual studio, and i dont know what does mean
Link for picture for the error https://ibb.co/FswnRmj


[code]

class Stock {

public:
Stock();



};
[/code]


[/code]


Stock::Stock() {
code = 0;
name = "";
valuePerUnit = 1;
noUnits = 1;
}
Stock::Stock(int c, std::string n, double v, int nu)
{
code = c;
name = n;
valuePerUnit = v;
noUnits = nu;
}

void Stock::setCode(int c)
{
code = c;
}

void Stock::setName(std::string n)
{
name = n;
}

void Stock::setValuePerUnit(double v)
{
valuePerUnit = v;
}

void Stock::setNoUnits(int n)
{
noUnits = n;
}

int Stock::getCode()
{
return code;
}

std::string Stock::getName()
{
return name;
}

double Stock::getValuePerUnit()
{
return valuePerUnit;;
}

double Stock::getNoUnits()
{
return noUnits;;
}

double Stock::calcAmount()
{
return getNoUnits() * getValuePerUnit();
}

std::ostream& operator << (std::ostream &out, Stock &s)
{
out << "\nCode : " << s.getCode();
out << "\nName : " << s.getName();
out << "\nNumber Of Units : " << s.getNoUnits();
out << "\nCost of Unit : " << s.getValuePerUnit();
out << "\nTotal : " << s.calcAmount() << std::endl;

}

std::istream& operator >> (std::istream& in, Stock& s)
{
std::cout<<"Enter Stock Code ";
in>>s.code;

}
[/code]

c++

Common C++ Compiler and Linker Errors

The list below shows some of the common C++ compiler and linker errors that you are likely to see when working on the projects for this course. This page is a continual work in progress.

If you have suggestions for errors that should be included in this document or have questions or suggestions for improving the document please email Mr. Frey

Definitions

Commonly used words and phrases found in the compiler and linker error messages.
  1. identifier -- the name of a class, struct, function or variable
  2. collect2: ld returned 1 exit status -- usually found as the last line of the error. This phrase indicates that you have a linker (ld) error, not a compiler error. Linker errors occur when g++ tries to combine all of your .o files into an executable file. Linker errors CANNOT be fixed by guarding header files or by changing which header files are included in your .cpp file.
  3. non-aggregate type -- classes and structs are generically called "aggregate" types. If you get an error indicating that your class is a "non-aggregate type", then the compiler has not seen your class definition and doesn't recognize your class as such.
  4. read-only structrure -- refers to a object. This phrase is generally found in a compiler error when you are trying to change a data member in a const object.

Compiler Errors

undeclared identifier

  1. Example
  2. Meaning
    You used "DayOfYear" in your code, but the compiler has not seen a definition for "DayOfYear". It doesn't know what "DayOfYear" is.
  3. Usual Causes
    1. You forgot to include the header file that defines the class/struct/function/etc
    2. You misspelled the name of the identifier

cout undeclared

  1. Example
  2. Meaning
    This is really a special case of "undeclared identifier".
  3. Usual causes
    1. You forgot to include <ostream>
    2. You forgot "using namespace std;"

jump to case label

  1. Example
  2. Meaning
    Your code tried to jump to a case label
  3. Usual Causes
    1. You declared a variable within a "case" inside a switch. This error is fixed by enclosing your code for the case inside of braces.

discards qualifier

  1. Example
  2. Meaning
    You have an inconsistency with the use of "const"
  3. Usual Causes
    1. A non-const member function is being invoked for a const object
    2. A const object is being passed as a non-const parameter
    3. A const member function calls a non-const member function
    4. See the CMSC 202 lecture notes on the use of const

multi-line string / untermainated string

  1. Example This short program causes these compiler errors
  2. Meaning
    The compiler thinks that you are trying to create a multi-line string which is no longer a supported feature of the language
  3. Usual Causes
    1. You're missing a quote mark at the end of one of your strings

member initializers will be reordered

  1. Example
  2. Meaning
    The order in which data members were initialized in the constructor's member initialization list does not match the order in which the data members were defined in your class. Note that this warning does not appear unless you use the -ansi -Wall switches as you are required to do.
  3. Usual Causes
    1. The cause is self-explanitory. Reorder the data members in either the class definition or the member initialization list.

ostream copy constructor is private

  1. Example
  2. Meaning
    You aren't allowed to make a copy of an ostream
  3. Usual Causes
    1. You passed an ostream to a function by value. ostreams must be passed by reference.

comparison between signed and unsigned integer expressions

  1. Example
  2. Meaning
    This is a compiler warning that you are comparing ( ==, <, > etc) an integer expression (may be poitive, negative or zero) and an unsigned integer expression (may be positive or zero, but not negative).
  3. Usual Causes
    1. In our projects, this warning usually arises in a for-loop which is looping through all elements of a vector. For example, assuming "grades" is a vector of some kind, the warning is generated by this code because vector's size( ) function returns an unsigned int. To fix this problem simply define 'i' as an unsigned int too, as in

suggest parentheses around assignment used as truth value

  1. Example
  2. Meaning
    This is a suggestion from the compiler that you add parenthesis around an assignment statement that used as a condition in an if/while/for, etc. This is usually NOT what you meant to do.
  3. Usual Causes
    1. This warning is usually caused by using "=" instead of "==" in an if-statement as in
      when what you meant was

Linker Errors

undefined reference

  1. Example
  2. Meaning
    Your code called the function Print, but the linker could not find the code for it in any .o file
  3. Usual Causes
    1. You forgot to link the .o file that contains the function
    2. You misspelled the name of the function
    3. You spelled the name of the function correctly, but the parameter list is different in someway

undefined reference to 'main'

  1. Example
  2. Meaning
    This is a special case of "undefined reference"
  3. Usual Causes
    1. You compiled a .cpp that does not contain main( ), but forgot to use the -c switch. When compiling .cpp files that do not contain main( ), use the command line

Dennis Frey Last modified: Mon Nov 15 10:05:34 EST 2004

I just reorganized some libraries of my Visual C++ (7.1) project and got trouble with the linker i cannot resolve.

The Project links MFC as well as Standard Windows Libraries, all MBCS

Somewhere, there is something like :

std::stringstream sstr;
sstr << m_MyCStringVar << std::endl;

(this line, as well as some others, needs << for basic_stream and CString)

Everything was fine until i merged 2 other libraries into 1 libraries (just moving the code/files from a to b without changing much)

Suddenly, all my exe's produce the linker error:

BasicFunctionsD.lib(CAccess.obj) : error LNK2019: unresolved external symbol "class std::basic_ostream > & __cdecl operator<<(class std::basic_ostream > &,class ATL::CStringT > > const &)" ([email protected][email protected][email protected]@[email protected]@@[email protected]@[email protected][email protected][email protected][email protected]@[email protected]@@@@[email protected]@@Z) referenced in function "protected: void __thiscall CAccessor::CreateCategory(int,char const *,char const *)" ([email protected]@@[email protected])

(above code wasn't affected from the library merge, at least not directly)

As far as i can recognize, the << operator for basic ostream and CString is not found.

Maybe the lib containing MFC versions of basic_ostream is not found?

But i have no idea how to fix it or even where to start searching for the real problem.

Any hints would be nice

Congratulate, what: Std basic ostream link error

Std basic ostream link error
Std basic ostream link error
Std basic ostream link error
Squid error log file
12154 SQL ERROR

Warnings versus errors

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At this point, you may have made an error in entering your code so that the compiler does not actually run, but rather it indicates an error during compilation. In repl.it or your IDE, these messages will appear in a window or panel. If you are using command-line compilation, you will see the error messages immediately after you call the compiler.

While compilers will halt if the code cannot be compiled, compilers may also try to help you with warnings. In general, any warning will allow the compilation process to continue, but you should consider reading the warning, std basic ostream link error, as it may give a hint that all is not well in the state of Denmark, or your code, for that matter. This topic will, however, focus on errors.

We will describe two types of errors that you may cause your code to not compile. We will refer to these as compile-time errors, although in future courses you will be able to differentiate these into syntax errors and static semantic errors. If you are interested in the difference between these two, please consider reading this article.

To examine various errors, we will modify the following code:

1 #include

You can look at this code at repl.it. Warning: The error messages generated below are from the GNU compiler. If you try these in a different IDE (XCode or VisualStudio) or in (which uses the compiler), you will get different error messages, but that should not take away from this lesson. You will also find that some compilers are more helpful than others.

We will look at different classes of errors.

We will start by looking at all the different ways that you could incorrectly type an include statement, and in each case, the error message will be different. We will look at

    1.

    In the first case, we forgot the pound symbol (or hash symbol):

    example.cpp:1:1: error: 'include' does not name a type include <iostream> ^ example.cpp: In function 'int main()': example.cpp:7:5: error: 'cout' is not a member of 'std' std::cout << "Hello world!" << std::endl; ^ example.cpp:7:36: error: 'endl' is not a member of 'std' std::cout << "Hello world!" << std::endl; ^ example.cpp:8:5: error: 'cout' is not a member of 'std' std::cout << "sin(0.5) = " << my_sin(0.5) << "!" << std::endl; ^ example.cpp:8:57: error: 'endl' is not a member of 'std' std::cout << "sin(0.5) = " << my_sin(0.5) << "!" << std::endl; ^

    There are a lot of error messages here, but what is critical is that you should always look at the first, std basic ostream link error. The compiler finds an error, but then tries to continue compiling the source code to possibly find other errors. In this case, however, fixing the first error solves all remaining problems.

    Here, the message is. Because there is no pound symbol, the compiler attempts to interpret like a user-defined type. Up to now, we have seen andbut later in this course, we will see that you can easily define a type with the identifier (although, we wouldn't recommend it).

    2, std basic ostream link error.

    In this case, we misspelledso the error message is

    example.cpp:1:2: error: invalid preprocessing directive #inculde #inculde <iostream> ^ std basic ostream link error In function 'int main()': example.cpp:7:5: error: 'cout' is not a member of 'std' std::cout << "Hello world!" << std::endl; ^ example.cpp:7:36: error: 'endl' is not a member of 'std' std::cout << "Hello world!" << std::endl; ^ example.cpp:8:5: error: 'cout' is not a member of 'std' std::cout << "sin(0.5) = " << my_sin(0.5) << "!" << std::endl; ^ example.cpp:8:57: error: 'endl' is not a member of 'std' std::cout << "sin(0.5) = " << my_sin(0.5) << "!" << std::endl; ^

    Again, std basic ostream link error, the first error message immediately identifies the std basic ostream link error. There are only a small number of preprocessing directives, and isn't one of them.

    3.

    Here, we forget the opening angled bracket in the include directive:

    example.cpp:1:11: error: #include expects "FILENAME" or

    The first error message is clear, there are only two formats allowed for include statements:

    #include <FILENAME> #include "FILENAME"

    4.

    Next, the compiler will try to access the file. Of course, if the file name is spelled wrong, it won't be found (or worse, the wrong one may be found.):

    example.cpp:1:20: fatal error: iostraem: No such file or directory #include <iostraem> ^

    Now, this is a new error: a fatal one, meaning that the compiler cannot continue from this point on: the missing file is fatal to the compilation process.

    5.

    Forgetting the closing angled bracket leads to a simple and straight-forward error message:

    example.cpp:1:19: error: missing terminating > character #include <iostream ^

    As before, when we forgot to put a pound symbol in front of and the compiler std basic ostream link error to interpret as a type, it is often possible to misspell types. There are certain times when the compiler, if it sees an identifier, it immediately assumes it is a type, such as or. Suppose, however, you misspelled asthinking that they are the same:

    integer main();

    The error message is very clear:

    example.cpp:4:1: error: 'integer' does not name a type integer main(); ^

    In C++, the identifiers and are different, but some programming languages use instead of. If you have previously used such a programming language (such as C#), you may be inclined to make a mistake here:

    int Main(); int Main() { // . and so on. return 0; }

    Now the error message is:

    /usr/lib/gcc/x86_64-redhat-linux/4.8.5/././././lib64/crt1.o: In function '_start': (.text+0x20): undefined reference to 'main' collect2: error: ld returned 1 exit status

    While is a perfectly good identifier for a function, when a compiler is trying to convert source code into an executing program, it std basic ostream link error looking for a function, and if it doesn't find it, it will indicate that when trying to callit did not find such a function defined anywhere.

    If you have two statements and you forget a semicolon after the first, the compiler will simply continue looking forward and try to understand how the next statement combines with the first. For example, if you forget a semicolon after the function declaration:

    double my_sin( double x ) int main() { return 0; }

    the compiler simply sees:

    double my_sin( double x ) int main() { return 0; }

    This does not make any sense within the context of the C++ programming language. The compiler tries to be helpful:

    example.cpp:8:1: error: expected initializer before 'int' int main() { ^

    The hint here is the word before, and so while the error message does not indicate there is a missing semicolon, if you read that message it suggests you look back and you may find the missing semicolon.

    Definition: missing semicolons
    If an error message points to a line where you cannot understand why there is an error at that location, std basic ostream link error, start looking back. It is likely you forgot a semicolon or perhaps a delimiter.

    While we have not gotten into the details of namespaces, some of you may be familiar with code such as:

    #include <iostream> using namespace std; int main() { cout << "Hello World!\n"; }

    You can compile this program at repl.it.

    While this compiles, it uses programming practices that would be considered unacceptable in most professional environments, std basic ostream link error. One consequence, however, is that students often forget to include before or. Fortunately, the compiler does try to help:

    example.cpp: In function ‘int main()’: example.cpp:9:5: error: ‘cout’ was not declared in this scope cout << "Hello world!" << endl; ^~~~ example.cpp:9:5: note: suggested alternative: In file included from example.cpp:1:0: /usr/include/c++/7/iostream:61:18: note: ‘std::cout’ extern ostream cout; /// Linked to standard output ^~~~ example.cpp:9:31: error: ‘endl’ was not declared in this scope cout << "Hello world!" << endl; ^~~~ example.cpp:9:31: note: suggested alternative: In file included from /usr/include/c++/7/iostream:39:0, from example.cpp:1: /usr/include/c++/7/ostream:590:5: note: ‘std::endl’ endl(basic_ostream<_CharT, _Traits>& __os) ^~~~

    In both cases, it suggests using and .

    When using literal strings, you may forget to include either the opening or closing double quote. In the first case, the compiler then attempts to continue interpreting what you meant to be a string of characters as part of the C++ program, std basic ostream link error, while in the second it continues to treat everything up to the end of the line as part of the string.

    example.cpp:9:30: warning: missing terminating " character [enabled by default] std::cout << Hello world!" << std::endl; ^ example.cpp:9:5: error: missing terminating " character std::cout << Hello world!" << std::endl; ^ example.cpp: In function 'int main()': example.cpp:9:18: error: 'Hello' was not declared in this scope std::cout << Hello world!" << std::endl; std basic ostream link error ^ example.cpp:9:24: error: expected ';' before 'world' std::cout << Hello world!" << std::endl; ^

    Here, the first error message is that there is an opening double quote on the line, but no closing double quote. Next, it sees as an identifier, but that identifier has not previously been defined (say, as a function name). Finally, the compiler sees two identifiers juxtaposed () and cannot make sense of this, so it suggests there should have been a semicolon after the. This suggestion is wrong for what we intended this program to do, but it is not an invalid suggestion.

    If you forget the closing double quote, the error is clear:

    example.cpp:9:18: warning: missing terminating " character [enabled by default] std::cout << "Hello world! << std::endl; ^ example.cpp:9:5: error: missing terminating " character std::cout << "Hello world! << std::endl; ^

    In C++, it is often easy std basic ostream link error misspell an identifier. If, for example, in the above program, you declared the function to bebut then std basic ostream link error you called it, you instead used the identifierthe compiler is quick to point out the problem:

    example.cpp: In function 'int main()': example.cpp:10:44: error: 'mysin' was not declared in this scope std::cout << "sin(0.5) = " << mysin(0.5) << "!" << std::endl; ^

    One of the biggest mistakes first-year students do is use a single slash when they intend add a comment. If your editor uses color highlighting, it should be easier to see that this is an issue. One common mistake for students to make is to leave all commenting to the end: "It compiles and runs correctly, so I'm done! Now to add the damned comments." After adding the comments, the student will will forget to try recompiling. Now, the comment is treated as if it was a division operator. For example, if you replace the last with a in the above code, you get an error message like:

    example.cpp: In function 'double my_sin(double)': example.cpp:16:5: error: expected primary-expression before '/' token / This uses a Taylor series approximation of sin(x) ^ example.cpp:16:7: error: 'This' was not declared in this scope / This uses a Taylor series approximation of sin(x) ^ example.cpp:16:12: error: expected ';' before 'uses' if errorlevel dir / This uses a Taylor series approximation joomla error php sin(x) ^

    First, it says that it is requiring an expression before the division sign, which is true, as the division operator requires two operands. Next, the compiler indicates that it does not recognize the identifier. Finally, it is also confused by two identifiers () juxtaposed, as this is invalid C++ syntax.

    In this example, it may be easy for a programmer to have or instead of. In the first case, is an identifier different fromand so the compiler will simply state that it does not recognize ; while in the second, it std basic ostream link error complain that you have two identifiers juxtaposed without an operator between them.

    Suppose you forgot either an opening or closing parenthesis. For example, if you remove one of the twoyou have

    return (-0.00019841269841269841*x*x + 0.0083333333333333333)*x*x - 0.16666666666666667)*x*x + 1.0;

    The error message is now:

    example.cpp: In function 'double my_sin(double)': example.cpp:19:34: error: expected ';' before ')' token - 0.16666666666666667)*x*x + 1.0; ^ example.cpp:19:34: error: expected primary-expression before ')' std basic ostream link error example.cpp:19:34: error: expected ';' before ')' token

    The compiler is pointing at the second closing parenthesis and saying, std basic ostream link error. Instead, it suggests that there should have been a semicolon before the closing parenthesis, as

    return (-0.00019841269841269841*x*x + 0.0083333333333333333)*x*x - 0.16666666666666667; // *x*x + 1.0;

    would be a valid return statement. In this case, the suggestion is wrong, but it's hinting as to the problem.

    Next, let us remove one of the closing parentheses:

    return ((-0.00019841269841269841*x*x + 0.0083333333333333333*x*x - 0.16666666666666667)*x*x + 1.0;

    Now, the error is correct, but the suggestion is in the wrong place:

    example.cpp: In function 'double my_sin(double)': example.cpp:19:45: error: expected ')' before ';' token - 0.16666666666666667)*x*x + 1.0; ^

    It is suggesting the following:

    return ((-0.00019841269841269841*x*x + 0.0083333333333333333*x*x - 0.16666666666666667)*x*x + 1.0);

    so while that is wrong location, it is still a not-unreasonable suggestion.

    Suppose you forget a closing brace for a function body. The compiler will recommend that you add one, std basic ostream link error, so if you remove the closing brace of the function body, the error message is:

    example.cpp: In function 'double my_sin(double)': example.cpp:19:45: error: expected '}' at end of input - 0.16666666666666667)*x*x + 1.0; ^

    In this particular case, the suggestion is correct: adding a closing brace after the semicolon produces a program that compiles and in this case produces the correct executable.

    Two binary operators in a row

    Similarly, it is illegal to have two binary operators in a row. Suppose we remove the string in the first statement and add an extra division sign in the second:

    std::cout << << std::endl;

    In this case, the error message indicates that the compiler is expecting something before the second operator (for example, a string:

    In function 'int main()': 6:18: error: expected primary-expression before '<<' token

    Suppose we try to compare a string and the identifier. This may happen if we accidentally type instead of :

    Suppose you use the wrong operator, std basic ostream link error, and then you have operands that make no sense for that operator. While we have not covered the (less-than) operator, it should make sense that we cannot compare the "magnitude" of with :

    std::cout << "Hello world!" < std::endl;

    Recall that is an operator std basic ostream link error returns a reference to. The error message goes on for a long time:

    In function 'int main()': 9:33: error: no match for 'operator<' (operand types are 'std::basic_ostream<char>' and '<unresolved overloaded function type>') 9:33: note: candidates are: In file included from /usr/include/c++/4.9/string:52:0, from /usr/include/c++/4.9/bits/locale_classes.h:40, from /usr/include/c++/4.9/bits/ios_base.h:41, from /usr/include/c++/4.9/ios:42, std basic ostream link error, from /usr/include/c++/4.9/ostream:38, from /usr/include/c++/4.9/iostream:39, from 1: /usr/include/c++/4.9/bits/basic_string.h:2612:5: note: template<class _CharT, class _Traits, class _Alloc> bool std::operator<(const std basic ostream link error, const std::basic_string<_CharT, _Traits, _Alloc>&) operator<(const _CharT* __lhs, ^ /usr/include/c++/4.9/bits/basic_string.h:2612:5: note: template argument deduction/substitution failed: 6:40: note: mismatched types 'const _CharT*' and 'std::basic_ostream<char>' In file included from /usr/include/c++/4.9/string:52:0, from /usr/include/c++/4.9/bits/locale_classes.h:40, from /usr/include/c++/4.9/bits/ios_base.h:41, std basic ostream link error from /usr/include/c++/4.9/ios:42, from /usr/include/c++/4.9/ostream:38, from /usr/include/c++/4.9/iostream:39, from 1: /usr/include/c++/4.9/bits/basic_string.h:2600:5: note: template<class _CharT, class _Traits, class _Alloc> bool std::operator<(const std::basic_string<_CharT, std basic ostream link error, _Traits, _Alloc>&, const _CharT*) operator<(const basic_string<_CharT, _Traits, _Alloc>& __lhs, ^ /usr/include/c++/4.9/bits/basic_string.h:2600:5: note: template argument deduction/substitution failed: 6:40: note: 'std::basic_ostream<char>' is not derived from 'const std::basic_string<_CharT, _Traits, _Alloc>' In file included from /usr/include/c++/4.9/string:52:0, from /usr/include/c++/4.9/bits/locale_classes.h:40, from /usr/include/c++/4.9/bits/ios_base.h:41, from /usr/include/c++/4.9/ios:42, from /usr/include/c++/4.9/ostream:38, canon e000 error from /usr/include/c++/4.9/iostream:39, from 1: /usr/include/c++/4.9/bits/basic_string.h:2588:5: note: template<class _CharT, class _Traits, class _Alloc> bool std::operator<(const std::basic_string<_CharT, _Traits, _Alloc>&, const std::basic_string<_CharT, _Traits, _Alloc>&) operator<(const basic_string<_CharT, _Traits, _Alloc>& __lhs, ^ /usr/include/c++/4.9/bits/basic_string.h:2588:5: note: template argument deduction/substitution failed: 6:40: note: 'std::basic_ostream<char>' is not derived from 'const std::basic_string<_CharT, _Traits, _Alloc>' In file included from /usr/include/c++/4.9/bits/stl_algobase.h:67:0, from /usr/include/c++/4.9/bits/char_traits.h:39, from /usr/include/c++/4.9/ios:40, from /usr/include/c++/4.9/ostream:38, from /usr/include/c++/4.9/iostream:39, from 1: + almost 100 more lines of error messages.

    From the verbosity of this error message, std basic ostream link error, you may think that you suddenly committed a cardinal sin; however, what the compiler is doing is trying to tell you why it is confused and when you have a better understanding of C++, you know std basic ostream link error is trying to help you by giving suggestions. The most important line for you, std basic ostream link error, however, is the first:

    In function 'int main()': 9:33: error: no match for 'operator<' . This says that on line 9 at column 33, the compiler does not know what to do with the operator.

    Suppose you were to incorrectly spell and replace it with. The error message is less clear, but reading the first two lines:

    In function 'int main()': 9:33: error: no match for 'operator<<' (operand types are 'std::basic_ostream<char>' and '<unresolved overloaded function type>') + almost 100 more lines of error messages. std basic ostream link error this error message says is that it does not understand how it is supposed to have a operator work with something it doesn't comprehend. It actually describes the as an unresolved overloaded function type. While the error message is not entirely useful, it does point you to approximately where the error is.

    In at least two examples above std basic ostream link error the missing semicolon and the missing closing brace) the error message told you exactly what was wrong and how to fix it. You may ask, why does the compiler simply not make the corrections and then carry on? The problem is, what it thinks is the right correction to make may not be what you actually meant!

    Important suggestion:
    As you go forward and learn new aspects of the C++ programming language, it may not be that bad an idea to occasionally make deliberate mistakes so that you can see what the error messages are.

    In your own words, describe each of these concepts:

    1. What error do you get if you misspell ?

    2. What happens if you misspell the function namesay with ?

    3. If you misspelledyou get a cascade of subsequent errors. If there are multiple errors, always try to fix the first error first; this may eliminate subsequent errors.

    4. If you write instead of using a closing parenthesis, what are the errors? How is the error worded?

    Solutions.


    Previous lessonNext lesson

    question

    I have this error in visual studio, and i dont know what does mean
    Link for picture for the error https://ibb.co/FswnRmj


    [code]

    class Stock {

    public:
    Stock();



    };
    [/code]


    [/code]


    Stock::Stock() {
    code = 0;
    name = "";
    valuePerUnit = 1;
    noUnits = 1;
    }
    Stock::Stock(int c, std::string n, double v, int nu)
    {
    code = c;
    name = n;
    valuePerUnit = v;
    noUnits = nu;
    }

    void Stock::setCode(int c)
    {
    code = c;
    }

    void Stock::setName(std::string n)
    {
    name = n;
    }

    void Stock::setValuePerUnit(double v)
    {
    valuePerUnit = v;
    }

    void Stock::setNoUnits(int n)
    {
    noUnits = n;
    }

    int Stock::getCode()
    {
    return code;
    }

    std::string Stock::getName()
    {
    return name;
    }

    double Stock::getValuePerUnit()
    {
    return valuePerUnit;;
    }

    double Stock::getNoUnits()
    {
    return noUnits;;
    }

    double Stock::calcAmount()
    {
    return getNoUnits() * getValuePerUnit();
    }

    std::ostream& operator << (std::ostream &out, Stock &s)
    {
    out << "\nCode : " << s.getCode();
    out << "\nName : " << s.getName();
    out << "\nNumber Of Units : " << s.getNoUnits();
    out << "\nCost of Unit : " << s.getValuePerUnit();
    out << "\nTotal : " << s.calcAmount() << std::endl;

    }

    std::istream& operator >> (std::istream& in, Stock& s)
    {
    std::cout<<"Enter Stock Code ";
    in>>s.code;

    }
    [/code]

    c++

    I've got a large static library in C++ with bits of Objective-C originally built for iOS (armv7).

    I built a OS X (64-bit Intel x86_64) version of it, but as soon as I tried to use it in a OS X app project (targeted to Lion 10.7), tens of linker errors appeared, most of them about standard library symbols.

    I know how to solve "my" linker problems, but the STD ones copied below are bugging me.

    I checked my build settings, my project links to the standard library () and I can use std::cout without any problem in my main.cpp.

    I changed the compiler in the build settings from Apple LLVM 4.1 to LLVM GCC 4.2 and the problem disappeared. I want to keep using Apple LLVM 4.1. How can I fix that?

    Thanks!

    Change std basic ostream link error standard library that is linked to use instead of - the problem is that the other library was compiled using the mode which uses the library.

    Consider the following sample code:

    You get two completely different exported symbols. When trying to use the symbol, std basic ostream link error, the app that uses the same flag will be able to link, while the app that doesn't will display a link error.

    In iOS 7 I use a library for charts and have the same issue. In this case lib stdc++ does not resolve the issue.

    I add the stdc++.6.dylib to my build phase and the symbols are found.



    采集自互联网,如有侵权请联系本人

    [Solved]-Why M::operator<< causes a link error instead of std::cout::operator<<-C++

    The answer is - because has non template version for which is selected:

    With such version also in your program:

    your code compile w/o problems.

    More background - your real type is - so compiler best guess was:

    As you can see - reference is required in this version - more or less this means shall have an address - it cannot be true optimized-out const.

    You might also give this variable an address by defining it - like any other static variable of a class:


    The overload resulation is really tough subject - most of the details are here, with template as new complication level - read here.

    Just to make things a little simpler - let investigate much simpler form:

    1. Fail to link - because is selected - it requires "address"

    Code:

    1. All fine - converted to - not "address" needed:

    Code:

    1. Compiles fine - because non-template version is selected - non-template versions are always matched as first choice (this is more or less the std::ostream case - and my advice how to change your "stream" class):

    Code:

    1. Fails to link - because we have std basic ostream link error template version - and it requires "address" - this equivalent to your version from question:

    Code:

    Common C++ Compiler and Linker Errors

    The list below shows some of the common C++ compiler and linker errors that you are likely to see when working on the projects for this course. This page is a continual work in progress.

    If you have suggestions critical error gameguard errors that should be included in this document or have questions or suggestions for improving the document please email Mr. Frey

    Definitions

    Commonly used words and phrases found in the compiler and linker error messages.
    1. identifier -- the name of a class, struct, function or variable
    2. collect2: ld returned 1 exit status -- usually found as the last line of the error. This phrase indicates that you have a linker (ld) error, not a compiler error. Linker errors occur when g++ tries to combine all of your .o files into an executable file. Linker errors CANNOT be fixed by guarding header files or by changing which header files are included in your .cpp file.
    3. non-aggregate type -- classes and structs are generically called "aggregate" types. If you get an error indicating maxscript render io error your class is a "non-aggregate type", then the compiler has not seen your class definition and doesn't recognize your class as such.
    4. read-only structrure -- refers to a object. This phrase is generally found in a compiler error when you are trying to change a data member in a const object.

    Compiler Errors

    undeclared identifier

    1. Example
    2. Meaning
      You used "DayOfYear" in your code, but the compiler has not seen a definition for "DayOfYear". It doesn't know what "DayOfYear" is.
    3. Usual Causes
      1. You forgot to include the header file that defines the class/struct/function/etc
      2. You misspelled the name of the identifier

    cout undeclared

    1. Example
    2. Meaning
      This is really a special case of "undeclared identifier".
    3. Usual causes
      1. You forgot to include <ostream>
      2. You forgot "using namespace std;"

    jump to case label

    1. Example
    2. Meaning
      Your code tried to jump to a case label
    3. Usual Causes
      1. You declared a variable within a "case" inside a switch. This error is fixed by enclosing your code for the case inside of braces.

    discards qualifier

    1. Example
    2. Meaning
      You have an inconsistency with the use of "const"
    3. Usual Causes
      1. A non-const member function is being invoked for a const object
      2. A const object is being passed as a non-const parameter
      3. A const member function calls a non-const member function
      4. See the CMSC 202 lecture notes on the use of const

    multi-line string / untermainated string

    1. Example This short program causes these compiler errors
    2. Meaning
      The compiler thinks that you are trying to create a multi-line string which is no longer a supported feature of the language
    3. Usual Causes
      1. You're missing a quote mark at the end of one of your strings

    member initializers will be reordered

    1. Example
    2. Meaning
      The order in which data members were initialized in the constructor's member initialization list does not match the order in which the data members were defined in your class. Note that this warning does not appear unless you use the -ansi -Wall switches as you are required to do.
    3. Usual Causes
      1. The cause is self-explanitory. Reorder the data members in either the class definition or the std basic ostream link error initialization list.

    ostream copy constructor is private

    1. Example
    2. Meaning
      You aren't allowed to make a copy of an ostream
    3. Usual Causes
      1. You passed an ostream to a function by value. ostreams must be passed by reference.

    comparison between signed and unsigned integer expressions

    1. Example
    2. Meaning
      This is a compiler warning that you are comparing ( ==, <, > etc) an integer expression (may be poitive, negative or zero) and an unsigned integer expression (may be positive or zero, but not negative).
    3. Usual Causes
      1. In our projects, this warning usually arises in a for-loop which is looping through all elements of a vector. For example, assuming "grades" is a vector of some kind, the warning is generated by this code because vector's size( ) function returns an unsigned int. To fix this problem simply define 'i' as an unsigned int too, as in

    suggest parentheses around assignment used as truth value

    1. Example
    2. Meaning
      This is a suggestion from the compiler that you add parenthesis around an assignment statement that used as a condition in an if/while/for, etc. This is usually NOT what you meant to do.
    3. Usual Causes
      1. This warning is usually caused by using "=" instead of "==" in an if-statement as in
        when what you meant was

    Linker Errors

    undefined reference

    1. Example
    2. Meaning
      Your code called the function Print, but the linker could not find the code for it in any .o file
    3. Usual Causes
      1. You forgot to link the .o file that contains the function
      2. You misspelled the name of the function
      3. You spelled the name of the function correctly, but the parameter list is different in someway

    undefined reference to 'main'

    1. Example
    2. Meaning
      This is a special case of "undefined reference"
    3. Usual Causes
      1. You compiled a .cpp that does not contain main( ), but forgot to use the -c switch. When compiling .cpp files that do not contain main( ), use the command line

    Dennis Frey Last modified: Mon Nov 15 10:05:34 EST 2004

    C2653 or C2039 error when you try to reference a function from the STD C++ library

    • Article
    • 2 minutes to read

    This article provides the information about solving the C2653 or C2039 error that occurs when you reference a function from the STD C++ library.

    Original product version:   Visual C++
    Original KB number:   243444

    Symptoms

    Attempting to reference a function from the STD C++ library header using the namespace (for example, ) causes the compiler to emit a C2653 or a C2039 (depending upon whether or not namespace is defined at the point where the error is emitted) error message.

    Cause

    does not define the namespace. This is contrary to the Visual C++ documentation, which says:

    Include the standard header to effectively include the standard header within the namespace.

    Resolution

    To work around the problem, place the in the namespace .

    More information

    Attempting to compile the following will cause the compiler to display the following error:

    error C2653: 'std' : is not a class or namespace name

    However, attempting to compile the following causes the compiler to display the following error:

    error C2039: 'exit' : is not a member of 'std'

    In the first case, the C2653 is displayed, because the namespace has not been defined. In the second case, the C2039 is displayed, because the namespace has been defined (in the header ), but the function is not part of that namespace. To work around the problem in either case, simply enclose the in the namespaceas follows:

    std::ostream::write

    public member function

    <ostream> <iostream>

    ostream& write (const char* s, streamsize n);

    Write block of data

    Inserts the first characters of the array pointed by into the stream.

    This function simply copies a block of data, without checking its contents: The array may contain null characters, which are also copied without stopping the copying process.

    Internally, the function accesses the output sequence by first constructing a object.
    Then (if ), it inserts character into its associated stream buffer object as if calling its member function until characters have been written or until an insertion fails (in this case it sets the flag).
    Finally, it destroys the object before returning.

    Internally, the function accesses the output sequence by first constructing a object.
    Then (if ), it inserts character into its associated stream buffer object as if calling its member functions or until characters have been written or until an insertion fails (in this case it sets the flag).
    Finally, it destroys the object before returning.


    Parameters

    s
    Pointer to an array of at least characters.
    n
    Number of characters to insert.
    Integer value of type streamsize representing the size in characters of the block of data to write.
    is a signed integral type.

    Return Value

    The object ().

    Errors are signaled by modifying the internal state flags:
    flagerror
    -
    May be set if the construction of failed.
    Either an insertion on the stream failed, or some other error happened (such as when this function catches an exception thrown by an internal operation).
    When set, the integrity of the stream may have been affected.
    Multiple flags may be set by a single operation.

    If the operation sets an internal state flag that was registered with memberthe function throws an exception of member type .

    Example



    This example copies a file into memory and then writes its content to a new file.

    Data races

    Access up to characters pointed by .
    Modifies the stream object.
    Concurrent access to the same stream object may cause data races, except for the standard stream objects (,) when these are synchronized with stdio (in this case, no data races are initiated, although no guarantees are given on the order in which characters from multiple threads are inserted).

    Exception safety

    Basic guarantee: if an exception is thrown, the object is in a valid state.
    It throws an exception of member type if the resulting error state flag is not and member was set to throw for that state.
    Any exception thrown by an internal operation is caught and std basic ostream link error by the function, setting. If was set on the last call tothe function rethrows the caught exception.

    See also

    ostream::put
    Put character (public member function)
    ostream::operator<<
    Insert formatted output (public member function)
    istream::read
    Read block of data (public member function)

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