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‎chapter07/7-3.c‎

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/*
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* Exercise 7-3. Revise minprintf to handle more of the other facilities of
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* printf.
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* Note: flags (excepts for left adjust) and variable width and length are not implemented.
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* By Faisal Saadatmand
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*/
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#include <stdio.h>
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#include <stdarg.h>
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#include <ctype.h>
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#include <stdlib.h>
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#include <string.h>
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#define MAXNUMB 20
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#define FLT_PRCISION 6
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#define FIELD_WIDTH 1
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/* macros */
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#define PRINT_N(la,x,w,v, nc) (la) ? (nc += printf("%-*" # x, w, v)) : \
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(nc += printf("%*" #x, w, v))
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#define PRINT_D(la,x,w,p,v,nc) (la) ? (nc += printf("%-*.*" # x, w, p, v)) : \
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(nc += printf("%*.*" # x, w, p, v))
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int minprintf(char *, ...);
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/* minprintf: minimal printf with variable argument list */
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int minprintf(char *fmt, ...)
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{
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va_list ap; /* points to each unnamed arg in turn */
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char *p, *sval, number[MAXNUMB];
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int ival, i, width, precision, nchar = 0;
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double dval;
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unsigned uval;
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void *pval;
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int leftAdjust, *pival;
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va_start(ap, fmt); /* make ap point to 1st unnamed arg */
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for (p = fmt; *p; p++) {
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if (*p != '%') {
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putchar(*p);
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++nchar;
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continue;
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}
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leftAdjust = 0;
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width = 1;
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precision = -1;
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if (*++p == '-') {
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leftAdjust = 1; /* left adjust */
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++p;
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}
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if (isdigit(*p)) { /* get width */
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for (i = 0; isdigit(*p) && i < MAXNUMB; i++)
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number[i] = *p++;
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number[i] = '\0';
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width = atoi(number);
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}
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if (*p == '.') {
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++p;
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for (i = 0; isdigit(*p) && i < MAXNUMB; i++) /* get precision pts */
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number[i] = *p++;
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number[i] = '\0';
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precision = atoi(number);
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}
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switch (*p) {
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case 'd':
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ival = va_arg(ap, int);
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PRINT_N(leftAdjust, d, width, ival, nchar);
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break;
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case 'i':
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ival = va_arg(ap, int);
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PRINT_N(leftAdjust, i, width, ival, nchar);
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break;
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case 'o':
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uval = va_arg(ap, int);
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PRINT_N(leftAdjust, o, width, uval, nchar);
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break;
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case 'x':
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uval = va_arg(ap, int);
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PRINT_N(leftAdjust, x, width, uval, nchar);
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break;
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case 'X':
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uval = va_arg(ap, int);
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PRINT_N(leftAdjust, X, width, uval, nchar);
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break;
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case 'u':
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uval = va_arg(ap, int);
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PRINT_N(leftAdjust, u, width, uval, nchar);
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break;
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case 'c':
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ival = va_arg(ap, int);
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PRINT_N(leftAdjust, c, width, ival, nchar);
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break;
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case 's':
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sval = va_arg(ap, char *);
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if (precision < 0)
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precision = strlen(sval);
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PRINT_D(leftAdjust, s, width, precision, sval, nchar);
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break;
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case 'f':
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dval = va_arg(ap, double);
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if (precision < 0)
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precision = FLT_PRCISION;
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PRINT_D(leftAdjust, f, width, precision, dval, nchar);
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break;
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case 'e':
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dval = va_arg(ap, double);
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if (precision < 0)
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precision = FLT_PRCISION;
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PRINT_D(leftAdjust, e, width, precision, dval, nchar);
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break;
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case 'E':
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dval = va_arg(ap, double);
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if (precision < 0)
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precision = FLT_PRCISION;
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PRINT_D(leftAdjust, E, width, precision, dval, nchar);
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break;
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case 'g':
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dval = va_arg(ap, double);
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PRINT_N(leftAdjust, g, width, dval, nchar);
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break;
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case 'G':
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dval = va_arg(ap, double);
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PRINT_N(leftAdjust, G, width, dval, nchar);
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break;
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case 'p':
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pval = va_arg(ap, void *);
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PRINT_N(leftAdjust, p, width, pval, nchar);
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break;
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case 'n':
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pival = va_arg(ap, int *);
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*pival = nchar;
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break;
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default:
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putchar(*p);
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++nchar;
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break;
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}
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}
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va_end(ap); /* clean up when done */
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return nchar;
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}
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int main(void)
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{
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minprintf("minprintf() output:\n");
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minprintf("%s\n", "hello, world");
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minprintf("%10s\n", "hello, world");
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minprintf("%.10s\n", "hello, world");
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minprintf("%-10s\n", "hello, world");
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minprintf("%.15s\n", "hello, world");
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minprintf("%-15s\n", "hello, world");
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minprintf("%15.10s\n", "hello, world");
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minprintf("%-15.10s\n", "hello, world");
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printf("\n");
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printf("printf() output:\n");
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printf("%s\n", "hello, world");
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printf("%10s\n", "hello, world");
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printf("%.10s\n", "hello, world");
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printf("%-10s\n", "hello, world");
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printf("%.15s\n", "hello, world");
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printf("%-15s\n", "hello, world");
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printf("%15.10s\n", "hello, world");
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printf("%-15.10s\n", "hello, world");
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return 0;
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}
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‎chapter07/7-4.c‎

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/*
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* Exercise 7-4. Write a private version of scanf analogous to minprintf from
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* the previous section.
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* By Faisal Saadatmand
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*/
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#include <stdio.h>
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#include <stdarg.h>
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#include <ctype.h>
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int minscanf(char *, ...);
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int minscanf(char *format, ...)
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{
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va_list ap;
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char *p, *sval, *cval;
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int *ival;
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float *fval;
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unsigned *uval;
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int nchar = 0;
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va_start(ap, format); /* make ap point to 1st unnamed arg */
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for (p = format; *p; p++) {
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if (*p != '%')
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continue;
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switch (*++p) {
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case 'd':
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ival = va_arg(ap, int *);
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nchar += scanf("%d", ival);
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break;
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case 'i':
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ival = va_arg(ap, int *);
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nchar += scanf("%i", ival);
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break;
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case 'o':
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uval = va_arg(ap, unsigned *);
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nchar += scanf("%u", uval);
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break;
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case 'c':
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cval = va_arg(ap, char *);
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nchar += scanf("%c", cval);
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break;
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case 's':
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sval = va_arg(ap, char *);
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nchar += scanf("%s", sval);
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break;
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case 'e':
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fval = va_arg(ap, float *);
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nchar += scanf("%e", fval);
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break;
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case 'f':
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fval = va_arg(ap, float *);
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nchar += scanf("%f", fval);
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break;
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case 'g':
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fval = va_arg(ap, float *);
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nchar += scanf("%g", fval);
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break;
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default:
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break;
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}
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va_end(ap);
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}
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return nchar;
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}
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int main(void) {
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int x, y, z;
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int nchar;
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printf("Enter an integer: ");
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nchar = minscanf("%i %i %i", &x, &y, &z);
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printf("%i %i %i\n", x, y, z);
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printf("Number of elements: %i\n", nchar);
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return 0;
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}

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