C程序找区域

Question

我遇到以下代码问题:

#include<stdio.h>
#include<conio.h>
float area_crcl(int);
float area_rect(int,int);

void main()
 {
 int n,a,b,r;
 float area;
 clrscr();
  printf("\nEnter your choice-\n1.Area of circle\n2.Area of Square\n3.Area of Rectangle\n");
  scanf("%d",&n);
   switch(n)
     {
     case 1:printf("\nEnter the radius of circle..\n");
        scanf("%d",&r);
        area=area_crcl(r);
        printf("\nArea of circle is %d\n",area);
        break;

     case 2:printf("\nenter the edge of square\n");
        scanf("%d",&a);
        area=area_rect(a,a);
        printf("\nArea of square is %d\n",area);
        break;

     case 3:printf("\nenter the lenght n breadth of rectangle\n");
        scanf("%d%d",&a,&b);
        area=area_rect(a,b);
        printf("\nArea of rectangle is %d\n",area);
        break;

     default:printf("\nU entered wrong choice..\n");
   }
  getch();
 }

 float area_crcl(int r)
   {
    float area;
    area=3.14*r*r;
    return area;
   }

 float area_rect(int a,int b)
   {
    float area;
    area=a*b;
    return area;
   }

我得到的输出是:

输入您的选择 - 1.Area of​​ circle 2.Area of​​ Square 3.Area of​​ Rectangle 1

输入圆的半径.2

圆的面积是0

为什么我输出0？

Answer 1

您的打印声明是:

printf("\nArea of circle is %d\n",area);

area是一个float你正在使用的%d格式字符串,用于int变量.这是行不通的-使用%e,%f,%g,或%a.