Error trying to use pthread on Ubuntu

Question

I'm reading a tutorial about threads in C++ and tested the following code:

#include <iostream>
#include <pthread.h>
#include <cstdlib>

using namespace std;

#define NUM_THREADS     5

void *PrintHello(void *threadid)
{
   long tid;
   tid = (long)threadid;
   cout << "Hello World! Thread ID, " << tid << endl;
   pthread_exit(NULL);
}

int main ()
{
   pthread_t threads[NUM_THREADS];
   int rc;
   int i;
   for( i=0; i < NUM_THREADS; i++ ){
      cout << "main() : creating thread, " << i << endl;
      rc = pthread_create(&threads[i], NULL, 
                      PrintHello, &threads[i]);
      if (rc){
         cout << "Error:unable to create thread," << rc << endl;
         exit(-1);
      }
   }
   pthread_exit(NULL);
}

I've tried to compile this code using both gcc and g++, but I always get compilation errors.

Using gcc -pthread thread_test.c:

/tmp/ccmpQLyp.o: In function PrintHello(void*)': thread_test.cpp:(.text+0x1a): undefined reference tostd::cout' thread_test.cpp:(.text+0x1f): 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*)' thread_test.cpp:(.text+0x2e): undefined reference tostd::ostream::operator<<(long)' thread_test.cpp:(.text+0x33): undefined reference to std::basic_ostream<char, std::char_traits<char> >& std::endl<char, std::char_traits<char> >(std::basic_ostream<char, std::char_traits<char> >&)' thread_test.cpp:(.text+0x3b): undefined reference tostd::ostream::operator<<(std::ostream& (*)(std::ostream&))' /tmp/ccmpQLyp.o: In function main': thread_test.cpp:(.text+0x63): undefined reference tostd::cout' thread_test.cpp:(.text+0x68): 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*)' thread_test.cpp:(.text+0x75): undefined reference tostd::ostream::operator<<(int)' thread_test.cpp:(.text+0x7a): undefined reference to std::basic_ostream<char, std::char_traits<char> >& std::endl<char, std::char_traits<char> >(std::basic_ostream<char, std::char_traits<char> >&)' thread_test.cpp:(.text+0x82): undefined reference tostd::ostream::operator<<(std::ostream& (*)(std::ostream&))' thread_test.cpp:(.text+0xcc): undefined reference to std::cout' thread_test.cpp:(.text+0xd1): undefined reference tostd::basic_ostream >& std::operator<< >(std::basic_ostream >&, char const*)' thread_test.cpp:(.text+0xde): undefined reference to std::ostream::operator<<(int)' thread_test.cpp:(.text+0xe3): undefined reference tostd::basic_ostream >& std::endl >(std::basic_ostream >&)' thread_test.cpp:(.text+0xeb): undefined reference to std::ostream::operator<<(std::ostream& (*)(std::ostream&))' /tmp/ccmpQLyp.o: In function__static_initialization_and_destruction_0(int, int)': thread_test.cpp:(.text+0x141): undefined reference to std::ios_base::Init::Init()' thread_test.cpp:(.text+0x150): undefined reference tostd::ios_base::Init::~Init()' /tmp/ccmpQLyp.o:(.eh_frame+0x47): undefined reference to `__gxx_personality_v0' collect2: error: ld returned 1 exit status

Can you help? Do I have to do something so this code runs on Linux and Windows?

Answer 1

Use g++ instead of gcc, or link -lstdc++ manually.

Answer 2

For anyone reading this in 2020:

In GCC, when linking against pthread, don't use "-lpthread", but just the "-pthread" CLI options.