//The bitwise operators abstract away the endianness. 
//For example, the >> operator always shifts the bits towards the least significant digit.
 
#include <stdio.h>
#include <stdint.h>

int main(void) {
    FILE *f1 = fopen("test1", "w");
    FILE *f2 = fopen("test2", "w");
    FILE *f3 = fopen("test3", "w");
    
    uint8_t data[] = {0xAB, 0xCD};                               
    size_t ret = fwrite(data, 1, 2, f1);
    printf("I wrote %lu items\n", ret);

    uint16_t x = 0xABCD;     
    ret = fwrite(&x, 2, 1, f2);
    printf("I wrote %lu items\n", ret);

    // Portable way
    uint8_t low_byte  = x & 0xFF;       //0xABCD
                                        //10101011 11001101
                                        //00000000 11111111 0xFF
                                        //00000000 11001101

    uint8_t high_byte = x >> 8;         //00000000 10101011
        
    
    fputc(low_byte, f3);
    fputc(high_byte, f3);

    fclose(f1);
    fclose(f2);
    fclose(f3);

    return 0;
}