Re: How to print an array of char backward.

On May 30, 8:34 pm, hank <ilona-radema...@xxxxxxxxxxx> wrote:

  do {
    if (dec % 2 == 0)
      strcat(bin, "0");
    else {
      strcat(bin, "1");
      dec--;
    }
    dec = dec / 2;
  } while (dec > 0);


This algorithm can be written differently depending on whether you do
or do not want leading zeroes.

My major criticism of your original code is that it takes a human
approach rather than a computer approach. A computer approach would be
to use (x & 1) instead of (x % 2), and also to use shifting instead of
division by 2.

If I didn't want leading zeroes, I'd go with something like the
following:

(Disclaimer: Untested code thrown together in the last two minutes)

#define QUANTITY_VALUE_BITS(int_type) /* fancy macro */

void GetBinary(unsigned const val, char *p)
{
unsigned mask = 1u << (QUANTITY_VALUE_BITS(unsigned) - 1);

do if (val & mask) goto We_Have_Ones;
while (mask >> = 1);

/* If here is reached, there's no 1's */
p[0] = '0';
p[1] = 0;
return; /* <--- And we're gone! */

We_Have_Ones:

*p++ = '1';

while (mask >>= 1) *p++ = (val & mask ? '1' : '0');

*p = 0;
}
.