Home/ Questions/Resolved the problem of the undefined reference to `std::cout'
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Otis Gagnon
  • 16
Asked: 2022-05-18T15:52:36+00:00 In:

Resolved the problem of the undefined reference to `std::cout’

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As advised, I used some code samples in another forum, but it could not improve the problem. My question is the “undefined reference to `std::cout’” in cpp – How to solve it?

The command line is:

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

and the result:

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
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

What does the message mean? Can you advise me to fix it? If you have other better answers, leave them in the answer box below.

undefined reference
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2 Answers

  1. Best Answer
    Expert

    The cause: I think the cause is that The C++ standard library contains cout, which requires explicit linking with -lstdc++ when using gcc; g++ automatically links the standard library.

    The solution: Compile the software using the following commands:

    g++ -Wall -Wextra -Werror -c main.cpp -o main.o
          ^^^^^^^^^^^^^^^^^^^^ <- When your code is compiled, you can use this command to get a list of all warnings.

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

    gcc main.cpp -lstdc++ -o main.o
    • 9

  2. Yes, g++ worked for me. 

    g++ my_source_code.cpp
    • 19

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