C/C++ Users Group Library 1996 July/C-C++ Users Group Library July 1996.iso/listings/v_07_01/v7n1033a.txt

Text File | 1989-02-13 | 4KB | 259 lines

/* stdarg example with prototypes */

#include <stdio.h>

int maxi(int, ...);

main()
{
    printf("-> %d\n", maxi(4, 10, 20, -5, 17));
    printf("-> %d\n", maxi(3, -10, -5, -17));

/* is type of second argument int or long? */

    printf("-> %d\n", maxi(3, 65432, -5, -17));

/* call maxi with count too small or too big */

    printf("-> %d\n", maxi(2, 10, -5, 17));
    printf("-> %d\n", maxi(4, 10, -5, 17));
}

#include <stdarg.h>
#include <limits.h>

int maxi(int parmn, ...)
{
    va_list ap;
    int i, j;
    int max = INT_MIN;

    va_start(ap, parmn);
    printf("%2d: ", parmn);

    for (j = 1; j <= parmn; ++j) {
        i = va_arg(ap, int);
        printf("%d, ", i);
        if (max < i)
            max = i;
    }

    va_end(ap);
    return (max);
}

 4: 10, 20, -5, 17, -> 20
 3: -10, -5, -17, -> -5
 3: -104, 0, -5, -> 0
 2: 10, -5, -> 10
 4: 10, -5, 17, 250, -> 250    /* ??? */





/* stdarg example without prototypes */

#include <stdio.h>

int maxi();

main()
{
    /* ... */
}

#include <stdarg.h>
#include <limits.h>

int maxi(parmn)
int parmn;
{
    /* ... */
}





/* varargs solution */

#include <stdio.h>

int maxi();

main()
{
    /* ... */
}

#include <varargs.h>
#include <limits.h>

int maxi(va_alist)
va_list va_alist;
/* or
va_decl
*/
{
    va_list ap;
    int i, j, k;
    int max = INT_MIN;

    va_start(ap);
    k = va_arg(ap, int);
    printf("%2d: ", k);

    for (j = 1; j <= k; ++j) {
        i = va_arg(ap, int);
        printf("%d, ", i);
        if (max < i)
            max = i;
    }

    va_end(ap);
    return (max);
}

 4: 10, 20, -5, 17, -> 20
 3: -10, -5, -17, -> -5
 3: -104, 0, -5, -> 0
 2: 10, -5, -> 10
 4: 10, -5, 17, 449, -> 449    /* ??? */





/* handling a variable number of values via an array */

#include <stdio.h>
#include <stddef.h>

int maxi1(size_t, int *);

main()
{
    static int array[5] = {4, 10, -7, 17, 20};
    size_t i;

    for (i = 1; i <= sizeof(array)/sizeof(int); ++i)
        printf("-> %d\n", maxi1(i, array));
}

#include <limits.h>

int maxi1(size_t count, int table[])
{
    size_t i;
    int max = INT_MIN;

    for (i = 0; i < count; ++i) {
        printf("%d, ", table[i]);
        if (max < table[i])
            max = table[i];
    }

    return (max);
}

4, -> 4
4, 10, -> 10
4, 10, -7, -> 10
4, 10, -7, 17, -> 17
4, 10, -7, 17, 20, -> 20






/* handling arguments with varying types */

#include <stdio.h>

int output(char *, ...);

main()
{
    output("S D C\nS X F E\n", "abcd", 123, 'A',
        "xyz", 0x12ab, 123.4, 123.4);
}

#include <stdarg.h>
#include <string.h>

int output(char *parmn, ...)
{
    va_list ap;
    int count = strlen(parmn);
    int j;

    va_start(ap, parmn);

    for (j = 1; j <= count; ++j) {
        switch (*parmn) {

/* string */    case 'S': {
            char *pc;

            pc = va_arg(ap, char *);
            printf("%s", pc);
            break;
        }

/* decimal */    case 'D': {
            int i;

            i = va_arg(ap, int);
            printf("%d", i);
            break;
        }

/* character */    case 'C': {
            int i;

            i = va_arg(ap, int);
            printf("%c", i);
            break;
        }

/* hex digit */    case 'X': {
            int i;

            i = va_arg(ap, int);
            printf("%x", i);
            break;
        }

/* double */    case 'F': {
            double d;

            d = va_arg(ap, double);
            printf("%f", d);
            break;
        }

/* exponent */    case 'E': {
            double d;

            d = va_arg(ap, double);
            printf("%e", d);
            break;
        }

        default: {
            putchar(*parmn);
            break;
        }
        }
        ++parmn;
    }

    va_end(ap);
}

abcd 123 A
xyz 12ab 123.400000 1.234000e+002