Undefined symbols for architecture x86_64: Which architecture should I use?

Question

I'm trying to do some really simple stuff in C++, but I can't find any information on how to tackle this. Even the book I have just says "Just compile and run the program".

test.cpp

#include <iostream> 
using namespace std;

int main() 
{ 
    cout << "Never fear, C++ is here!"; 
    return 0;
}

The compiler says:

Undefined symbols for architecture x86_64:
  "std::cout", referenced from:
      _main in ccVfJHGs.o
  "std::basic_ostream<char, std::char_traits<char> >& std::operator<< <std::char_traits<char> >(std::basic_ostream<char, std::char_traits<char> >&, char const*)", referenced from:
      _main in ccVfJHGs.o
  "std::ios_base::Init::Init()", referenced from:
      __static_initialization_and_destruction_0(int, int)in ccVfJHGs.o
  "std::ios_base::Init::~Init()", referenced from:
      ___tcf_0 in ccVfJHGs.o
ld: symbol(s) not found for architecture x86_64
collect2: ld returned 1 exit status

I tried compiling with flags like -arch i386 and -m32 but it always says it's the wrong architecture. Which one should I use?

I'm doing this on a Mac but not using XCode, just gcc.

Answer 1

The error isn't that it's the wrong architecture, it's that std::cout (and other symbols) isn't defined.

You should compile and link with g++ not gcc, to automatically link with correct C++ libraries.

Answer 2

The error is caused because you're compiling with gcc, which only default-links libc. You need to compile with g++ so that libstdc++ is auto-linked in too.

Answer 3

Use g++ instead of gcc to link with exact c++ libraries