3-7

#include<stdio.h>
int main(void)
{
    int digit,letter,other;
    char ch;
    int i;
    digit=letter=other=0;
    printf("Enter 10 characters:");
    for(i=1;i<=10;i++){
    ch=getchar();
    if((ch>='a'&&ch<='z')||(ch>='A'&&ch<='Z'))
    letter++;
    else if(ch>='0'&&ch<='9')
    digit++;
    else
    other++;
    }
    printf("letter=%d,digit=%d,other=%d\n",letter,digit,other);
    return 0;
}