Exercise 7.3. Revise minprintf to handle more of the other facilities of printf.

Exercise 7.3. Revise minprintf to handle more of the other facilities of printf.


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

#define MASFMT 10

/* minprintf: */
void minprintf(char *fmt, ...)
{
    va_list ap; //points to the next unnamed argument    
    char *p, *sval;
    int ival, i;
    unsigned uval;
    double dval;
    char masfmt[MASFMT]; //array of characters
   
    va_start(ap, fmt);//establishes for the first unnamed argument
    for(p = fmt; *p; p++)
    {
        if(*p != '%')
        {
            putchar(*p);
            continue;
        }
        i = 0;
        masfmt[i++] = '%';
        for(;*(p+1) && !isalpha(*(p+1)); i++)
            masfmt[i] = *++p;
        masfmt[i++] = *(p+1);//letter format        
        masfmt[i] = '\0';       
        switch (*++p) //letter format
        {
            case 'd':
            case 'i':
                ival = va_arg(ap, int);
                printf(masfmt, ival);
                break;
            case 'f':
                dval = va_arg(ap, double);
                printf(masfmt, dval);
                break;
            case 's':
                for(sval = va_arg(ap, char *); *sval; sval++)
                putchar(*sval);
                break;
            case 'o':
            case 'x':
            case 'X':
            case 'u':
            case 'e':
                uval = va_arg(ap, unsigned);
                printf(masfmt, uval);
                break;
            default:
                putchar (*p);
                break;
        }
    }
    va_end(ap);//clear, after finish
}