few ways Program to Find the machine is little endian or Big endian

following are the ways to find machine is little endian or big endian, and how to verify my program is working fine?

# 1
/* program to find machine is little endian or little endian */
#include<stdio.h>

int main()
{
int x=0x12345678;
char *p;
p=(char *)&x;
if(*p == 0x78) {
    printf("Little endian \n");
} else {
   printf("Big endian \n");
}
return 0;
}

#2
/* another correct way is using unions */
int main()
{

union e {
       int x;
       char y;
};

union e p1;
p1.x=0x12345678;

if(p1.y == 0x78) {
    printf("Little endian \n");
} else {
   printf("Big endian \n");
}
return 0;
}

#3
below is same as #1 with more simplified

shiv@ubuntu:~/ds/misc$
/* following is not correct way to find the machine */
#include<stdio.h>

int main()
{
int num=1;

if(*(char *)&num == 1)
{
printf("Little\n");
} else {
   printf("Big endian\n");
}

}

below is readelf utility we can verify our compiled binary is for little endian or bigendian?
so that what our program is answer match with readelf utility

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