作业3 应用分支与循环结构解决问题

/* 统计字符 */
#include<stdio.h>
int main(void)
{
    int digit,kong,letter,other;
    char ch;
    int i;
    digit=kong=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=='')||(ch=='\n')
            kong++;
        else if(ch>='0'&&ch<='9')
            digit++;
        else 
            other++;
    }
    printf("letter=%d,kong=%d,digit=%d,other=%d\n",letter,kong,digit,other);



    return 0;
}

 

/* 计算平均分，并统计几个人数 */
#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#%d:",i);
        scanf("%Lf",&grade);
        total=total+grade;
        if(grade>60){
            count++;
        }
    }
    printf("Grade average=%.2f\n",total/n);
    printf("Number of unfailures=%d\n",count);



    return 0;
}

 

/* 多分段函数 */
#include<stdio.h>
int main(void)
{
    double x,y;


    printf("Enter x:");
    scanf("%Lf",&x);
    if(x<0){
        y=-1;
    }
    else if(x=0){
            y=0;
    }
    else{
            y=1;
    }
    printf("f(%.2f)=%.2f\n",x,y);


    return 0;
}