作业p39

/*编程，计算两数字的和差积商余*/
#include<stdio.h>
int main(void)
{
    int num1,num2,sum,difference,product,quotient,remainder;
    /**/
    

    printf("Enter num1:");
    scanf("%d",&num1);
    printf("Enter num2:");
    scanf("%d",&num2);
    sum=num1+num2;
    printf("sum=%d
",sum);
    /*计算两数之和*/
    difference=num1-num2;
    printf("difference=%d
",difference);
    /*计算两数之差*/
    product=num1*num2;
    printf("product=%d
",product);
    /*计算两数乘积*/
    quotient=num1/num2;
    printf("quotient=%d
",quotient);
    /*计算两数之商*/ 
    remainder=num1%num2;
    printf("remainder=%d
",remainder);
    /*计算两数之余*/

    return 0;
}

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


    printf("Enter x(x>=0):
");
    scanf("%lf",&x);
    if(x<=50){
        y=0.53*x/3;
    }
    else{
        y=0.58*x-2.5;
    }
    printf("y=f(%f)=%.2f
",x,y);


    return 0;
}
/*实验中有*/

/*计算x的n次方*/
#include<stdio.h>
int main(void)
{    
    int a,x,n,i;    
    printf("Enter x:");    
    scanf("%d",&x);    
    printf("Enter n:");    
    scanf("%d",&n);    
    a=x;    
    for(i=1;i<n;i++)    
    {        
        x=x*a;    
}   /*进入循环，计算x的n次方*/
    printf("Enter result:");    
    printf("%d
",x);    
    return 0;
}

/*输入两个正整数m,n,求（i^2+1/i),从m到n的和*/ 
#include<stdio.h>
int main(void)
{
    int m,n,i;
    double product,result;
/*result为单个元素的解，product为所有解的和*/     
    printf("Enter m:");
    scanf("%d",&m);
    printf("Enter n:");
    scanf("%d",&n);

    product=0;
/*从m到n依次循环求解*/     
    for(i=m;i<=n;i++){
        result=(i*i)+(1/i);
        printf("%d",result);
/*将单个元素所求解累加起来*/         
    product=product+result;

    }
    printf("product=%.2f
",product);

    return 0;
}

/*输入一个正整数n，计算1-（2/3)+(3/5)-(4/7)+(5/9)-...的前n项和*/
#include<stdio.h>
int main(void)
{
    int i,n,numerator,denominator,flag;
    double sum,item;

    printf("Enter n:");
    scanf("%d",&n);
    numerator=1;
    denominator=1;
    sum=0;
    flag=1;

/*循环n次求解各项并相加求和*/    
    for(i=1;i<=n;i++){
        item=flag*(numerator*1.0/denominator);
        numerator=numerator+1;
        denominator=denominator+2;
        flag=-flag;
        sum=sum+item;
    }
    printf("sum=%lf
",sum);

    return 0;
}

/*输入正整数n，求2^1+2^2+……+2^n*/
#include<stdio.h>
#include<math.h>
int main(void)
{
    int n,i,power;
    double product;

    printf("Enter n:");
    scanf("%d",&n);
    product=0;
    for(i=1;i<=n;i++){/*进入循环*/
        power=pow(2,i);/*计算2的n次方*/        
        printf("%d",power)
        product=product+power;/*求和*/
    }
    printf("product=%.0f
",product);

    return 0;
}

#include<stdio.h>
double fact(int n);
int main(void)
{
    int i,n;
    double sum;

    printf("Enter n:");
    scanf("%d",&n);
    sum=0;
    for(i=0;i<=n;i++){
        sum=sum+fact(i);
        }
    printf("%d",sum);
    
    return 0;
}
double fact(int n)
{
    int i;
    double product;

    product=1;
    for(i=1;i<=n;i++){
        product=product*i;
    }

    return product;
}

#include<stdio.h>
int main(void)
{
    int x,y;
    printf("输入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,num,n;
    double grade,total;

    num=0;
    total=0;
    count=0;
    printf("Enter n:");
    scanf("%d",&n);
    printf("Enter grades:");
    scanf("%lf",&grade);

    while(grade>=0){
        total=total+grade;
        num++;
        if(grade>60)
            count++;
        scanf("%lf",&grade);
    }
    if(num!=0){
        printf("Grade average is%.2f
",total/num);
        printf("Number of success is %d
",count);
    }
    else
        printf("Grade average is0
");

    return 0;
}

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

    int i;
    digit=letter=other=blank=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("letter=%d,digit=%d,blank=%d
,other=%d
",letter,digit,blank,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("Right!
");
    }
    else{
        printf("Wrong!
");
    }
    }
    return 0;
    }

#include<stdio.h>
int main(void)
{
    int repeat;
    char ch;


    printf("Enter repeat:");
    scanf("%d",&repeat);
    ch = getchar();
    switch(ch){
    case'A':
        printf("grade=90~100
");
        break;
    case'B':
        printf("grade=80~89
");
        break;
    case'C':
        printf("grade=70~79
");
        break;    
    case'D':
        printf("grade=60~69
");
        break;
    case'E':
        printf("grade=0~59
");
        break;
    default:
        printf("Unknown operator
");
        break;
    }


    return 0;
}

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


    for(i=1;i<=5;i++){
        printf("[1]Select apple 
");
        printf("[2]Select rears 
");
        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);
    }


    printf("Thanks 
");


    return 0;
}