Error trying to use rand from std library cstdlib with g++

Question

I was trying to use the random function in Ubuntu compiling with g++ on a larger program and for some reason rand just gave weird compile errors. For testing purposes I made the simplest program I could and it still gives errors.

Program:

---

#include <iostream>

using std::cout;
using std::endl;

#include <cstdlib>

int main()
{
  cout << "Random number " << rand();

return 0;
}

Error when compiling with the terminal

sudo g++ chapter_3/tester.cpp ./test ./test: In function _start': /build/buildd/eglibc-2.10.1/csu/../sysdeps/i386/elf/start.S:65: multiple definition of_start' /usr/lib/gcc/i486-linux-gnu/4.4.1/../../../../lib/crt1.o:/build/buildd/eglibc-2.10.1/csu/../sysdeps/i386/elf/start.S:65: first defined here ./test:(.rodata+0x0): multiple definition of _fp_hw' /usr/lib/gcc/i486-linux-gnu/4.4.1/../../../../lib/crt1.o:(.rodata+0x0): first defined here ./test: In function_fini': (.fini+0x0): multiple definition of _fini' /usr/lib/gcc/i486-linux-gnu/4.4.1/../../../../lib/crti.o:(.fini+0x0): first defined here ./test:(.rodata+0x4): multiple definition of_IO_stdin_used' /usr/lib/gcc/i486-linux-gnu/4.4.1/../../../../lib/crt1.o:(.rodata.cst4+0x0): first defined here ./test: In function __data_start': (.data+0x0): multiple definition ofdata_start' /usr/lib/gcc/i486-linux-gnu/4.4.1/../../../../lib/crt1.o:(.data+0x0): first defined here ./test: In function __data_start': (.data+0x4): multiple definition of__dso_handle' /usr/lib/gcc/i486-linux-gnu/4.4.1/crtbegin.o:(.data+0x0): first defined here ./test: In function main': (.text+0xb4): multiple definition ofmain' /tmp/cceF0x0p.o:tester.cpp:(.text+0x0): first defined here ./test: In function _init': (.init+0x0): multiple definition ofinit' /usr/lib/gcc/i486-linux-gnu/4.4.1/../../../../lib/crti.o:(.init+0x0): first defined here /usr/lib/gcc/i486-linux-gnu/4.4.1/crtend.o:(.dtors+0x0): multiple definition of `_DTOR_END' ./test:(.dtors+0x4): first defined here /usr/bin/ld: error in ./test(.eh_frame); no .eh_frame_hdr table will be created. collect2: ld returned 1 exit status

Answer 1

You seem to be linking the file to itself, resulting in multiple definitions of symbols in the resulting executable. Try this instead:

g++ chapter_3/tester.cpp

Also don't use sudo for a command such as this.