big endian or little endian

#include <stdio.h>


typedef union 
{
    char cVar;
    unsigned int iVar;
}unionInt;

int main()
{
    unionInt tmp;
    tmp.iVar = 0x12345678;
    if(tmp.cVar == 0x78)
    {
        printf("least significant byte\n");
    }
    else if(tmp.cVar == 0x12)
    {
        printf(("most significant byte\n"));
    }


    return 0;
}