Write a C Program to prove we are working on little Endian environment using a union

Verifying Little Endian Environment with a Union in C

"writing a C program to prove we are working on a little-endian environment using a union" means creating a program in the C programming language that determines whether the computer it is running on is little-endian or big-endian.

In computing, endianness refers to the way in which bytes are ordered in a multi-byte data type, such as an integer. Little-endian means that the least significant byte is stored first, while big-endian means that the most significant byte is stored first.

The program will use a union, which is a special data type in C that allows two or more variables to share the same memory location. By assigning a value to one member of the union and then checking the value of another member, we can determine the byte order of the system.

Prove we are working on a little Endian environment using a union in  c

To prove that we are working on a little endian environment using a union in C, we can write the following program:

#include <stdio.h>
#include <stdint.h>
union {
  uint32_t i;
  char c[4];
} u;

int main() {
  u.i = 0x12345678;

  if (u.c[0] == 0x78) {
    printf("Little endian\n");
  } else {
    printf("Big endian\n");
  }

  return 0;
}

This program works by creating a union that contains both a 32-bit integer and an array of 4 characters. The union is then initialized with the value 0x12345678.

On a little endian machine, the least significant byte (LSB) is stored first. This means that the byte values in the array u.c will be:

u.c[0] = 0x78
u.c[1] = 0x56
u.c[2] = 0x34
u.c[3] = 0x12

On a big endian machine, the most significant byte (MSB) is stored first. This means that the byte values in the array u.c will be:

u.c[0] = 0x12
u.c[1] = 0x34
u.c[2] = 0x56
u.c[3] = 0x78

Therefore, we can determine whether the machine is little endian or big endian by checking the value of u.c[0]. If u.c[0] is equal to 0x78, then the machine is little endian. Otherwise, the machine is big endian.

To compile and run the program, you can use the following commands:

gcc -o endian endian.c
./endian

If you are running on a little endian machine, the program will print the following output:

Little endian

If you are running on a big endian machine, the program will print the following output:

Big endian