C++

C++ TutorialBasic input/output in c++C++ AlignmentC++ Argument Dependent Name LookupC++ Arithmitic MetaprogrammingC++ ArraysC++ Atomic TypesC++ AttributesC++ autoC++ Basic Type KeywordsC++ Bit fieldsC++ Bit ManipulationC++ Bit OperatorsC++ Build SystemsC++ C incompatibilitiesC++ C++11 Memory ModelC++ Callable ObjectsC++ Classes/StructuresC++ Client server examplesC++ Common compile/linker errors (GCC)C++ Compiling and BuildingC++ Concurrency with OpenMPC++ Const CorrectnessC++ const keywordC++ Constant class member functionsC++ constexprC++ ContainersC++ Copy ElisionC++ Copying vs AssignmentC++ Curiously Recurring Template Pattern (CRTP)C++ Date and time using chrono headerC++ Debugging and Debug-prevention Tools & TechniquesC++ decltypeC++ Digit separatorsC++ EnumerationC++ ExceptionsC++ Explicit type conversionsC++ Expression templatesC++ File I/OC++ Floating Point ArithmeticC++ Flow ControlC++ Fold ExpressionsC++ Friend keywordC++ function call by value vs. call by referenceC++ Function OverloadingC++ Function Template OverloadingC++ Futures and PromisesC++ Header FilesC++ Implementation-defined behaviorC++ Inline functionsC++ Inline variablesC++ IterationC++ IteratorsC++ KeywordsC++ LambdasC++ Layout of object typesC++ Linkage specificationsC++ LiteralsC++ LoopsC++ Memory managementC++ MetaprogrammingC++ Move SemanticsC++ mutable keywordC++ MutexesC++ NamespacesC++ Non-Static Member FunctionsC++ One Definition Rule (ODR)C++ Operator OverloadingC++ operator precedenceC++ OptimizationC++ Overload resolutionC++ Parameter packsC++ Perfect ForwardingC++ Pimpl IdiomC++ PointersC++ Pointers to membersC++ PolymorphismC++ PreprocessorC++ ProfilingC++ RAII: Resource Acquisition Is InitializationC++ Random number generationC++ Recursive MutexC++ Refactoring TechniquesC++ ReferencesC++ Regular expressionsC++ Resource ManagementC++ Return Type CovarianceC++ Returning several values from a functionC++ RTTI: Run-Time Type InformationC++ Scopes



C++ Common compile/linker errors (GCC)

From WikiOD

undefined reference to `***'[edit | edit source]

This linker error happens, if the linker can't find a used symbol. Most of the time, this happens if a used library is not linked against.

qmake:

LIBS += nameOfLib

cmake:

TARGET_LINK_LIBRARIES(target nameOfLib)

g++ call:

g++ -o main main.cpp -Llibrary/dir -lnameOfLib

One might also forget to compile and link all used .cpp files (functionsModule.cpp defines the needed function):

g++  -o binName main.o functionsModule.o

error: '***' was not declared in this scope[edit | edit source]

This error happens if a unknown object is used.

Variables[edit | edit source]

Not compiling:

#include <iostream>

int main(int argc, char *argv[])
{
    {
        int i = 2;
    }

    std::cout << i << std::endl; // i is not in the scope of the main function

    return 0;
}

Fix:

#include <iostream>

int main(int argc, char *argv[])
{
    {
        int i = 2;
        std::cout << i << std::endl;
    }

    return 0;
}

Functions[edit | edit source]

Most of the time this error occurs if the needed header is not included (e.g. using std::cout without #include <iostream>)

Not compiling:

#include <iostream>

int main(int argc, char *argv[])
{
    doCompile();

    return 0;
}

void doCompile()
{
    std::cout << "No!" << std::endl;
}

Fix:

#include <iostream>

void doCompile(); // forward declare the function

int main(int argc, char *argv[])
{
    doCompile();

    return 0;
}

void doCompile()
{
    std::cout << "No!" << std::endl;
}

Or:

#include <iostream>

void doCompile() // define the function before using it
{
    std::cout << "No!" << std::endl;
}

int main(int argc, char *argv[])
{
    doCompile();

    return 0;
}

Note: The compiler interprets the code from top to bottom (simplification). Everything must be at least declared (or defined) before usage.

fatal error: ***: No such file or directory[edit | edit source]

The compiler can't find a file (a source file uses #include "someFile.hpp").

qmake:

INCLUDEPATH += dir/Of/File

cmake:

include_directories(dir/Of/File)

g++ call:

g++ -o main main.cpp -Idir/Of/File

Credit:Stack_Overflow_Documentation