Question

Let’s say i have this number

int x = 65535;

Which is the decimal representation of:

ÿÿ

I know how i can do it from single char

#include <stdio.h>

int main() {
    int f = 65535;
    printf("%c", f);
}

But this will only give me “ÿ”

I would like to do this without using any external library, and preferably using C type strings.

Answer 1

#include <stdio.h>

int main() {
    unsigned f = 65535; // initial value

    // this will do the printf and ff >>= 8 until f <= 0 ( =0 actually)
    do {
      printf("%c", f & 0xff); // print once char. The &0xff keeps only the bits for one byte (8 bits)
      f >>= 8; // shifts f right side for 8 bits
    } while (f > 0);
}

Consider the value 65535, or 0xffff in hexadecimal, meaning its positive value takes 2 bytes that are 0xff and 0xff

• print of f & 0xff keeps only the 8 LSb, (0xffff & 0xff = 0xff)
• f >> = 8 shifts the value 8 bits to the right, 0xffff becomes 0x00ff (the ‘ff’ right side are gone
• f > 0 is true since f == 0xff now

Next loop is the same, but f >>= 8 shifts 0x00ff to the right => 0x0000, and f is null.
Thus the f > 0 condition is wrong and the loop ends.