Someone

#include <stdio.h>

int main()
{
    union {
        short s;
        char c[sizeof(short)];
    } un;
    un.s = 0x0102;
    if(sizeof(short) == 2)
    {
        if(un.c[0] == 1 && un.c[1] == 2)
            printf("big-endian\n");
        else if(un.c[0] == 2 && un.c[1] == 1)
            printf("little-endian\n");
        else
            printf("unknown\n");
    }
    else
    {
        printf("sizeof(short) = %d\n", sizeof(short));
    }
    return(0);
}