Don't know what's causing this bug

[Strogian]

OK, here's my program.

#include <stdio.h>
#include <string.h>

void minprintf(char *fmt, ...);

/* prints a few lines of output, to test minprintf */
int main()
{
int i = 321;
double ld = 43.5939232223;
char s[] = &quot;The quick brown fox jumps over the lazy dog.&quot;;

minprintf(&quot;%s\n&quot;, s);
minprintf(&quot;%10d %10.3s\n&quot;, i, s);
minprintf(&quot;%10.3lf %10.3s\n&quot;, ld, s);

return 0;
}

#include <stdarg.h>

/* minprintf: minimal printf with variable argument list */
void minprintf(char *fmt, ...)
{
va_list ap; /* points to each unnamed arg in turn */
char *p, *sval;
char cval;
int ival;
short int sival;
long int lival;
double dval;
long double ldval;
char opt[25];
int i;

va_start(ap, fmt); /* make ap point to 1st unnamed arg */
for (p = fmt; *p; p++) {
if (*p != '%') {
putchar(*p);
continue;
}
i = 0;
opt[i++] = '%';
if (*++p == '-') {
opt[i++] = '-';
p++;
}
while (isdigit(*p)) {
opt[i++] = *p;
p++;
}
if (*p == '.') {
opt[i++] = '.';
p++;
}
while (isdigit(*p)) {
opt[i++] = *p;
p++;
}
opt = '\0';
switch(*p) {
case 'c':
cval = va_arg(ap, char);
strcat(opt, &quot;c&quot;
printf(opt, cval);
break;
case 'd':
ival = va_arg(ap, int);
strcat(opt, &quot;d&quot;
printf(opt, ival);
break;
case 'f':
dval = va_arg(ap, double);
strcat(opt, &quot;f&quot;
printf(opt, dval);
break;
case 's':
sval = va_arg(ap, char *);
strcat(opt, &quot;s&quot;
printf(opt, sval);
break;
case 'h':
strcat(opt, &quot;h&quot;
switch (*++p) {
case 'd':
sival = va_arg(ap, short int);
strcat(opt, &quot;d&quot;
printf(opt, sival);
break;
default:
strcat(opt, p);
printf(&quot;%s&quot;, opt);
break;
}
break;
case 'l':
strcat(opt, &quot;l&quot;
switch (*++p) {
case 'd':
lival = va_arg(ap, long int);
strcat(opt, &quot;d&quot;
printf(opt, lival);
break;
case 'f':
ldval = va_arg(ap, long double);
strcat(opt, &quot;f&quot;
printf(opt, ldval);
break;
default:
strcat(opt, p);
printf(&quot;%s&quot;, opt);
break;
}
break;
default:
strcat(opt, p);
printf(&quot;%s&quot;, opt);
break;
}
}
va_end(ap); /* clean up when done */
}


Now, when I run it, here's what I get:
The quick brown fox jumps over the lazy dog.
321 The
43.594 ŠM

Everything works fine, except for that final time I try to print the string. Could someone help me with this? I'm thinking it has something to do with that long double argument not being completely read with va_arg, but I'm not sure.

 

[Strogian]

Nevermind, I figured it out. =) (I didn't declare ld as a long double in main(), and I needed to use %Lf for it, not %lf)