32位gcc和64位gcc与-m32选项有什么区别？

Question

My team have been working on JNI recently so we faced different issues regarding 32-bit and 64-bit architectures. Let's take an example ( temp.c ).

#include <stdio.h>
void main(){
  printf("long=%d\n",sizeof(long));
}

Is there any difference between gcc_32_bit temp.c and gcc_64_bit -m32 temp.c ?

Cases tested:

Case-1: code compiled on 64-bit ubuntu using gcc temp.c . Output: long=8 on 64-bit ubuntu.

Case-2: code compiled on 64-bit ubuntu using gcc -m32 temp.c . Output: long=4 on 64-bit ubuntu.

Case-3: code compiled on 64-bit MAC ( 64-bit cross compiler used ) using /usr/local/gcc-4.8.1-for-linux64/bin/x86_64-pc-linux-gcc temp.c . Output: long=8 on 64-bit ubuntu.

Case-4: code compiled on 64-bit MAC ( 32-bit cross compiler used ) using /usr/local/gcc-4.8.1-for-linux32/bin/i586-pc-linux-gcc temp.c . Output: Error: cannot run on 64-bit ubuntu.

We are using MAC cross compiler because we do not have 32-bit linux machine.

Answer 1

It could seem a little weird, but it has started working out of nowhere.

As amdn posted in comments above, it could be due to some missing library for 32-bit. Since it was not working earlier, I installed gcc-multilib and some auto updates of Ubuntu and it has started working.

Thank you everyone for your great help.