程序代码：

#include <stdio.h>
int main ()
{
    char a[100];
    int _number=0, _small=0, _big=0,_special=0;
    gets(a);
    char *p;
    for (p = a; *p != '\0'; p++)
    {
        if (*p >= '0' && *p <= '9')
            _number += 1;
        else if (*p >= 'a' && *p <= 'z')
            _small += 1;
        else if (*p >= 'A' && *p <= 'Z')
            _big += 1;
        else if (*p >=0 && *p <=126)
            _special += 1;
    }
    printf ("数字字符数量：%d\n小写字母字符数量：%d\n大写字母字符数量：%d\n特殊字符数量：%d\n", _number, _small, _big, _special);
    return 0;
}