20131002国庆作业例3-8,3-9,3-10,3-11

3-8

#include<stdio.h>
int main(void)
{
    int choice,i;
    double price;

    for(i=1;i<=5;i++){
        printf("[1]Select crisps 
");
        printf("[2]Select popcorn 
");
        printf("[3]Select chocolate 
");
        printf("[4]Select cola 
");
        printf("[0]exit 
");

        printf("Enter choice:");
        scanf("%d",&choice);

        if(choice==0)
            break;
        switch(choice){
            case 1:price=3.0;break;
            case 2:price=2.5;break;
            case 3:price=4.0;break;
            case 4:price=3.5;break;
            default:price=0.0;break;
        }
        printf("price=%0.1f
",price);
    }
      printf("Thanks 
");

      return 0;
}

 3-9

#include<stdio.h>
int main(void)
{
    double value1,value2;
    char op;

    printf("Type in an expression:");
    scanf("%lf%c%lf",&value1,&op,&value2);
    switch(op){
    case'+':
        printf("=%.2f
",value1+value2);
        break;
    case'-':
        printf("=%.2f
",value1-value2);
        break;
    case'*':
        printf("=%.2f
",value1*value2);
        break;
    case'/':
        printf("=%.2f
",value1/value2);
        break;
    }

    return 0;
}

 3-10

 

#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;
}

3-11

运行结果1

结果2

#include<stdio.h>
int main(void)
{
    double value1,value2;
    char op;

    printf("Type in an expression:");
    scanf("%lf%c%lf",&value1,&op,&value2);
    if(op=='+')
        printf("=%.2f
",value1+value2);
    else if(op=='-')
        printf("=%.2f
",value1-value2);
    else if(op=='*')
        printf("=%.2f
",value1*value2);
    else if(op=='/')
        if(value2!=0)
            printf("=%.2f
",value1/value2);
        else
            printf("Divisor can not be 0!
");
    else
        printf("Unknown operator!
");

    return 0;
}