num_digits.c


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#include<stdio.h>

/*
 * Count digits, whitespace, and other characters.
 */
main() {
    int c, i, nwhite, nother;
    int ndigit[10];

    nwhite = nother = 0;

    for (i = 0; i < 10; ++i)
        ndigit[i] = 0;

    while ((c = getchar()) != EOF)
        if (c >= '0' && c <= '9')
            ++ndigit[c - '0'];
        else if (c == ' ' || c == '\n' || c == '\t')
            ++nwhite;
        else 
            ++nother;

    printf("digits =");

    for (i = 0; i < 10; ++i)
        printf(" %d", ndigit[i]);
    printf(", whitespace = %d, other = %d\n",
            nwhite, nother);
}