Question

I know that to get the number of bytes used by a variable type, you use sizeof(int) for instance. How do you get the value of the individual bytes used when you store a number with that variable type? (i.e. int x = 125.)

Answer 1

You can get the bytes by using some pointer arithmetic:

int x = 12578329; // 0xBFEE19
for (size_t i = 0; i < sizeof(x); ++i) {
  // Convert to unsigned char* because a char is 1 byte in size.
  // That is guaranteed by the standard.
  // Note that is it NOT required to be 8 bits in size.
  unsigned char byte = *((unsigned char *)&x + i);
  printf("Byte %d = %u\n", i, (unsigned)byte);
}

On my machine (Intel x86-64), the output is:

Byte 0 = 25  // 0x19
Byte 1 = 238 // 0xEE
Byte 2 = 191 // 0xBF
Byte 3 = 0 // 0x00