作业 2 分支、循环结构

1.

#include<stdio.h>
int main(void)
{
    int num1,num2;
    char op;         /*自定义一个字符串类型的变量*/

    printf("Type in an expression:");    /*提示输入一个算式*/
    scanf("%d%c%d",&num1,&op,&num2);     /*输入一个整数，一个字符，一个整数*/

        if(op=='+')            /* 判断字符变量是否为+，若是则进行下行操作。下同 */
            printf("=%d
",num1+num2);
        else if(op=='-')
            printf("=%d
",num1-num2);
        else if(op=='*')
            printf("=%d
",num1*num2);
        else if(op=='/')
            printf("=%d
",num1/num2);
        else if(op=='%')
            printf("=%d
",num1%num2);
        else
            printf("Unknown operator
");

        return 0;
}

3.

#include<stdio.h>
int main(void)
{
    int i,n;
    double x,y;
    y=1;
    printf("Enter x and n:");
    scanf("%Lf%d",&x,&n);

    for(i=1;i<=n;i++){
        y=y*x;         /*计算x乘以本身n次*/
    }
    printf("y=%.2f",y);
    return 0;
}

4.

#include<stdio.h>
int main(void)
{
    int m,n,i;
    double y;
    y=0;
    printf("Enter m and n:");
    scanf("%d%d",&m,&n);

    for(i=m;i<=n;i++){
        y=y+i*i+1/i;
    }
    printf("y=%.2f
",y);

    return 0;
}

5.

#include<stdio.h>
int main(void)
{
 int i,n,x;
 double y;
 x=1;
 y=0;
 printf("Enter n:");
 scanf("%d",&n);

 for(i=1;i<=n;i++){
  y=y+(x*i)/(2*i-1);
  x=-x;
 }
 printf("y=%.2f
",y);

 return 0;
}

为神马运行出来结果永远是1？！到底错哪里了？！！！T^T。啊啊啊啊啊桑心死了。我真的要哭了啦！不管了先继续做下去了T T。

6.

#include<stdio.h>
#include<math.h>
int main(void)
{
    int year;
    double rate,money,loan,x;

    printf("Enter loan & rate:");
    scanf("%LfLf",&loan,&rate);

    for(year=5;year<=30;year++){
     x=pow(1+rate,12*year);  
     money=loan*rate*x/(x-1); 
     printf("year=%d,money=%.2f
",year,money); 
    }


    return 0;
}

7.

#include<stdio.h>
#include<math.h>
int main(void)
{
    int n,i,x;
    double y;

    printf("Enter n:");
    scanf("%d",&n);
    y=0;
    for(i=1;i<=n;i++){
        x=pow(2,i);
        y=y+x;
    }
    printf("y=%.2f
",y);

    return 0;
}