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#include <stdio.h>
#include <stdlib.h>
#include <stdarg.h>
void myprintf(const char *fmt, ...);
int main(int arg, char ** argv)
{
//system("pause");
myprintf("%d\n", 12);
myprintf("%x\n", 22);
myprintf("%%\n", 22);
myprintf("%%\n", 22);
myprintf("%%\n", 22);
myprintf("%%\n", 22);
myprintf("\n");
return 0;
}
void myprintf(const char *fmt, ...) /* format to be printed */
{
int c; /* next character in fmt */
int d;
unsigned long u; /* hold number argument */
int base; /* base of number arg */
int negative; /* print minus sign */
int ispercent; /* is 100%*/
static char x2c[] = "0123456789ABCDEF"; /* nr conversion table */
char ascii[8 * sizeof(long) / 3 + 2]; /* string for ascii number */
char *s; /* string to be printed */
va_list argp; /* optional arguments */
va_start(argp, fmt); /* init variable arguments */
while((c=*fmt++) != 0) {
if (c == '%') { /* expect format '%key' */
negative = 0; /* (re)initialize */
s = NULL; /* (re)initialize */
ispercent = 0; /* (re)initialize */
switch(c = *fmt++) { /* determine what to do */
/* Known keys are %d, %u, %x, %s, and %%. This is easily extended
* with number types like %b and %o by providing a different base.
* Number type keys don't set a string to 's', but use the general
* conversion after the switch statement.
*/
case 'd': /* output decimal */
d = va_arg(argp, signed int);
if (d < 0) { negative = 1; u = -d; } else { u = d; }
base = 10;
break;
case 'u': /* output unsigned long */
u = va_arg(argp, unsigned long);
base = 10;
break;
case 'x': /* output hexadecimal */
u = va_arg(argp, unsigned long);
base = 0x10;
break;
case 's': /* output string */
s = va_arg(argp, char *);
if (s == NULL) s = "(null)";
break;
case '%': /* output percent */
d = va_arg(argp, signed int);
if (d < 0) { negative = 1; u = -d; } else { u = d; }
base = 10;
ispercent = 1;
break;
/* Unrecognized key. */
default: /* echo back %key */
s = "%?";
s[1] = c; /* set unknown key */
}
/* Assume a number if no string is set. Convert to ascii. */
if (s == NULL) {
s = ascii + sizeof(ascii)-1;
*s = 0;
do { *--s = x2c[(u % base)]; } /* work backwards */
while ((u /= base) > 0);
}
/* This is where the actual output for format "%key" is done. */
if (negative) putchar('-'); /* print sign if negative */
while(*s != 0) { putchar(*s++); } /* print string/ number */
if (ispercent) { putchar('%');}
}
else {
putchar(c); /* print and continue */
}
} /* terminate output */
va_end(argp); /* end variable arguments */
}
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