undefined reference to 'std::cout'

问题

Shall this be the example:

#include <iostream>
using namespace std;
int main()
{
    cout << \"Hola, moondo.\\n\";
}

It throws the error:

gcc -c main.cpp gcc -o edit main.o  main.o: In function `main\':
main.cpp:(.text+0xa): undefined reference to `std::cout\'
main.cpp:(.text+0xf): undefined reference to `std::basic_ostream<char,std::char_traits<char> >& std::operator<< <std::char_traits<char>>(std::basic_ostream<char, std::char_traits<char> >&, char const*)\'
main.o: In function `__static_initialization_and_destruction_0(int,int)\':
main.cpp:(.text+0x3d): undefined reference to `std::ios_base::Init::Init()\'
main.cpp:(.text+0x4c): undefined reference to `std::ios_base::Init::~Init()\' collect2: error: ld
returned 1 exit status make: *** [qs] Error 1

Also, this example:

#include <iostream>
int main()
{
    std::cout<<\"Hola, moondo.\\n\";
}

throws the error:

gcc -c main.cpp gcc -o edit main.o  main.o: In function `main\':
main.cpp:(.text+0xa): undefined reference to `std::cout\'
main.cpp:(.text+0xf): undefined reference to `std::basic_ostream<char,std::char_traits<char> >& std::operator<<<std::char_traits<char>>(std::basic_ostream<char,std::char_traits<char> >&, char const*)\'
main.o: In function `__static_initialization_and_destruction_0(int,int)\': main.cpp:(.text+0x3d): undefined reference to `std::ios_base::Init::Init()\'
main.cpp:(.text+0x4c): undefined reference to `std::ios_base::Init::~Init()\' collect2: error: ld
returned 1 exit status make: *** [qs] Error 1

Note: I am using Debian Wheezy.

回答1:

Compile the program with:

g++ -Wall -Wextra -Werror -c main.cpp -o main.o
     ^^^^^^^^^^^^^^^^^^^^ <- For listing all warnings when your code is compiled.

as cout is present in the C++ standard library, which would need explicit linking with -lstdc++ when using gcc; g++ links the standard library by default.

With gcc, (g++ should be preferred over gcc)

gcc main.cpp -lstdc++ -o main.o

回答2:

Yes, using g++ command worked for me:

g++ my_source_code.cpp

回答3:

Makefiles

If you're working with a makefile and you ended up here like me, then this is probably what you're looking or:

If you're using a makefile, then you need to change cc as shown below

my_executable : main.o
    cc -o my_executable main.o

to

CC = g++

my_executable : main.o
    $(CC) -o my_executable main.o

来源：https://stackoverflow.com/questions/28236870/undefined-reference-to-stdcout