How to Check Endianness (Little vs Big Endian) in C

Endianness refers to the byte order in which multi-byte integers are stored in computer memory. Little-Endian architectures (x86_64, ARM) store the least significant byte at the lowest memory address, whereas Big-Endian architectures store the most significant byte first.

Checking CPU Endianness in C

#include <stdio.h>
 
int main(void) {
    unsigned int val = 0x01;
    char *c = (char *)&val;
 
    if (*c == 0x01) {
        printf("Architecture: Little-Endian (x86 / ARM)\n");
    } else {
        printf("Architecture: Big-Endian (Network Byte Order)\n");
    }
 
    return 0;
}