//There are no issues with endiannes for one byte values

#include <stdio.h>
#include <stdint.h>

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

    // Not portable
    uint16_t x = 0xABCD;     
    ret = fwrite(&x, 2, 1, f2);
    printf("I wrote %lu items\n", ret);
    
    fclose(f1);
    fclose(f2);

    return 0;
}