63 lines
1.3 KiB
C
63 lines
1.3 KiB
C
|
#include <stdio.h>
|
||
|
|
#include <stdlib.h>
|
||
|
|
#include <math.h>
|
||
|
|
#include <string.h>
|
||
|
|
#include <limits.h>
|
||
|
|
|
||
|
|
|
||
|
|
void itoa(int n, char s[], unsigned w);
|
||
|
|
|
||
|
|
/* passes args to itoa or INT_MIN if no arg is given */
|
||
|
|
int main(int argc, char *argv[])
|
||
|
|
{
|
||
|
|
int n, w;
|
||
|
|
n = (argc > 1) ? atoi(argv[1]) : INT_MIN;
|
||
|
|
w = (argc > 2) ? atoi(argv[2]) : (int)log10(abs(n)) + 1 + (n < 0);
|
||
|
|
|
||
|
|
if (w < 0) {
|
||
|
|
printf("error : invalid width %d\n", w);
|
||
|
|
return 1;
|
||
|
|
}
|
||
|
|
|
||
|
|
char s[w+1];
|
||
|
|
itoa(n, s, w);
|
||
|
|
printf("%s\n", s);
|
||
|
|
return 0;
|
||
|
|
}
|
||
|
|
|
||
|
|
void reverse(char *s);
|
||
|
|
|
||
|
|
/* itoa: convert n to characters (base 10) in s, pads with leading spaces
|
||
|
|
* to width w, truncates (left part) string of n if its is wider than w */
|
||
|
|
void itoa(int n, char s[], unsigned w)
|
||
|
|
{
|
||
|
|
int i = 0;
|
||
|
|
unsigned un = (n < 0) ? -n : n;
|
||
|
|
|
||
|
|
/* handle zero */
|
||
|
|
if (!n && w)
|
||
|
|
s[i++] = '0';
|
||
|
|
|
||
|
|
/* handle number */
|
||
|
|
for (; i < w && un > 0; un /= 10, i++) {
|
||
|
|
s[i] = un % 10 + '0';
|
||
|
|
}
|
||
|
|
/* handle sign */
|
||
|
|
if (n < 0 && i < w)
|
||
|
|
s[i++] = '-';
|
||
|
|
/* pad with spaces */
|
||
|
|
while (i < w)
|
||
|
|
s[i++] = ' ';
|
||
|
|
|
||
|
|
s[i] = '\0';
|
||
|
|
reverse(s);
|
||
|
|
}
|
||
|
|
|
||
|
|
/* reverse: reverses string s in place */
|
||
|
|
void reverse(char *s)
|
||
|
|
{
|
||
|
|
char c, *s2;
|
||
|
|
for (s2 = s + strlen(s) - 1; s < s2; s++, s2--)
|
||
|
|
c = *s, *s = *s2, *s2 = c;
|
||
|
|
}
|