小宝的习题2

#include<stdio.h> 
#include<math.h> 
int main() 
{  
    int i,n;
    double sum,item; 
    sum=0; 
    printf("input:n\n");  
    scanf("%d",&n); 
    for(i=0;i<=n;i++) 
    {  
        item=pow(2,i);  
        sum=sum+item;
    }   
    printf("sum=%lf\n",sum);

    return 0;
}

#include<stdio.h>
#include<math.h> 
int main()
 {  
    int lower,upper,month,year,loan;  
    double money,rate;  
    lower=5;upper=30;  
    printf("请输入贷款本金:loan\n");
    scanf("%d",&loan);  
    printf("请输入月利率:rate\n");  
    scanf("%lf",&rate);  
    printf("还款年限\t月还款额\n");  
    for(year=lower;year<=upper;year++)  
    {   
        month=year*12;   
        money=(loan*rate*pow((1+rate),month))/(pow((1+rate),month)-1);  
        printf("%d\t\t%lf\n",year,money);
    } 

    return 0;
} 

#include<stdio.h>  
void main() 
{  
    int num1,num2,y1,y2,y3,y5;
    double y4; 
    printf("请输入两个数：num1,num2\n");
    scanf("%d%d",&num1,&num2);   
    y1=num1+num2;   
    y2=num1-num2;   
    y3=num1*num2;  
    y4=num1*1.0/num2;  
    y5=num1%num2;  
    printf("num1,num2和y1=%d\nnum1,num2差y2=%d\nnum1,num2积y3=%d\nnum1,num2商y4=%lf\nnum1,num2余y5=%d\n",y1,y2,y3,y4,y5);  
}