From clc-wiki

The C Programming Language, 2nd Edition, by Kernighan and Ritchie
Exercise 7.03 on page 156

Revise minprintf to handle more of the other facilities of printf .

Solution by Gregory Pietsch

/* Gregory Pietsch - K&R2 Exercise 7-3 - 2001-01-28 gkp@flash.net */

#include <stdarg.h>
#include <stdio.h>

/* minprintf:  minimal printf with variable argument list */
void minprintf(char *fmt, ...)
{
    va_list ap;
    char *p, *sval;
    int ival;
    double dval;
    unsigned uval;

    va_start(ap, fmt);    /* make ap point to the first unnamed arg */
    for (p = fmt; *p; p++) {
        if (*p != '%') {
            putchar(*p);
            continue;
        }
        switch (*++p) {
        case 'd':
        case 'i':
            ival = va_arg(ap, int);
            printf("%d", ival);
            break;
        case 'c':
            ival = va_arg(ap, int);
            putchar(ival);
            break;
        case 'u':
            uval = va_arg(ap, unsigned int);
            printf("%u", uval);
            break;
        case 'o':
            uval = va_arg(ap, unsigned int);
            printf("%o", uval);
            break;
        case 'x':
            uval = va_arg(ap, unsigned int);
            printf("%x", uval);
            break;
        case 'X':
            uval = va_arg(ap, unsigned int);
            printf("%X", uval);
            break;
        case 'e':
            dval = va_arg(ap, double);
            printf("%e", dval);
            break;
        case 'f':
            dval = va_arg(ap, double);
            printf("%f", dval);
            break;
        case 'g':
            dval = va_arg(ap, double);
            printf("%g", dval);
            break;
        case 's':
            for (sval = va_arg(ap, char *); *sval; sval++)
                putchar(*sval);
            break;
        default:
            putchar(*p);
            break;
        }
    }
    va_end(ap);
}

/* end of function */