Exercise 7.4. Write a private version of scanf analogous to minprintf

Exercise 7.4. Write a private version of scanf analogous to minprintf from the previous section.


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

#define ARRAYFMT 10

void minscanf(char *, ...);


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