Printing leading zeroes for hexadecimal in C
Solution 1:
Use "%02x".
The two means you always want the output to be (at least) two characters wide.
The zero means if padding is necessary, to use zeros instead of spaces.
Solution 2:
result is a pointer, use a loop to print all the digits:
int i;
for (i = 0; i < 16; i++) {
printf("%02x", result[i]);
}