小宝的第三章2

#include<stdio.h>
int main(void)
{
    double valuel,value2;
    char op;

    printf("Type in an expression:");
    scanf("%lf%c%lf",&valuel,&op,&value2);
    if(op=='+')
        printf("=%.2f
",valuel+value2);
    else if(op=='-')
        printf("=%.2f
",valuel-value2);
    else if(op=='*')
        printf("=%.2f
",valuel*value2);
    else if(op=='/')
        if(value2!=0)
            printf("=%.2f
",valuel/value2);
        else
            printf("Divisor can not be 0!
");
        else
            printf("Unknown operator!
");

    return 0;
}

#include<stdio.h>
int main(void)
{
    int blank,digit,other;
    char ch;
    int i;
    blank=digit=other=0;
    printf("Enter 10 characters:");
    for(i=1;i<=10;i++){
        ch=getchar();

        switch(ch){
            case' ':
            case'
':
                blank++;
                break;
            case'0':case'1':case'2':case'3':case'4':
            case'5':case'6':case'7':case'8':case'9':
                digit++;
                break;
            default:
                other++;
                break;
        }
    }
    printf("blank=%d,digit=%d,other=%d
",blank,digit,other);

    return 0;
}

#include<stdio.h>
int main(void)
{
    double valuel,value2;
    char op;

    printf("Type in an expression:");
    scanf("%lf%c%lf",&valuel,&op,&value2);
    switch(op){
        case'+':
            printf("=%.2f
",valuel+value2);
            break;
        case'-':
            printf("=%.2f
",valuel-value2);
            break;
        case'*':
            printf("=%.2f
",valuel*value2);
            break;
        case '/':
            printf("=%.2f
",valuel/value2);
            break;
        default:
            printf("Unknown operator
");
            break;
    }

    return 0;
}