练习 1-14 编写一个程序，打印输入中各个字符出现频度的直方图。

 

#include <stdio.h>

/* count digits, white space, others */

int main(int argc, char const *argv[])
{
    int c, i, j, 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;
        }
    }

    for (i = 0; i < 10; ++i) {
        printf("%d:", i);
        for (j = 0; j < ndigit[i]; ++j) {
            printf("*");
        }
        printf("\n");
    }
    printf("w:");
    for (i = 0; i < nwhite; ++i) {
        printf("*");
    }
    printf("\no:");
    for (i = 0; i < nother; ++i) {
        printf("*");
    }
    printf("\n");

    return 0;
}