作业

#include <stdio.h>
int main(void)
{
    int x,y;
    printf("Enter x:");
    scanf("%d",&x);

    if(x<0){
        y=-1;
    }
    else if(x==0){
        y=0;
    }
    else{
        y=1;
    }
    printf("y=%d
",y);

    return 0;
}

#include <stdio.h>
int main(void)
{
    int count,i,n;
    double grade,total;

    printf("Enter n:");
    scanf("%d",&n);
    total=0;
    count=0;
    for(i=1;i<=n;i++){
        printf("Enter grade:",i);
        scanf("%lf",&grade);
        total=total+grade;
        if(grade>60){
            count++;
        }
    }
    printf("Grade average=%.2f
",total/n);
    printf("Number of successful=%d
",count);

    return 0;
}

#include <stdio.h>
int main(void)
{
    int blank,digit,letter,other;
    char ch;

    int i;
    blank=digit=letter=other=0;
    printf("Enter 15 characters:");
    for(i=1;i<=15;i++){
        ch=getchar( );
        if((ch>='a'&&ch<='z')||(ch>='A'&&ch<='Z'))
            letter++;
        else if(ch>='0'&&ch<='9')
            digit++;
        else if((ch=' ')&&ch<=' ') 
            blank++;
        else
            other++;
    }
    printf("blank=%d,letter=%d,digit=%d,other=%d
",blank,letter,digit,other);

    return 0;
}

#include<stdio.h>
int main(void)
{
    int i,year,n;    
    printf("Enter n:");
    scanf("%d",&n);

    for(i=1;i<=n;i++){
        printf("Enter year:");
        scanf("%d",&year);

        if((year%4==0&&year%100!=0)||(year%400==0)){
            printf("该年是闰年
");
    }
    else{
        printf("该年不是闰年
");
    }
    }
    return 0;
}

#include<stdio.h>
int main(void)
{
    char ch;
    printf("enter Level: ");
    ch=getchar();
    switch(ch){
        case 'A':printf("%c 90-100
",ch);break; 
        case 'B':printf("%c 80-89
",ch);break;
        case 'C':printf("%c 70-79
",ch);break;
        case 'D':printf("%c 60-69
",ch);break;
        case 'E':printf("%c 0-59
",ch);break;
            default: printf("0
");
    }

    return 0;
}

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

    for(i=1;i<=5;i++){
        printf("[1]Select apples
");
        printf("[2]Select pears
");
        printf("[3]Select oranges
");
        printf("[4]Select grapes
");
        printf("[0]exit
");

        printf("Enter choice:");
        scanf("%d",&choice);
        
        if(choice==0)
            break;
        switch(choice){
            case 1:price=3.00;break;
            case 2:price=2.50;break;
            case 3:price=4.10;break;
            case 4:price=10.20;break;
            default:price=0.00;break;
        }

        printf("price=%0.2f
",price);
    }
        return 0;
    }