则么用C语言编写一个简单的计算机程序要求会加减乘除开根号

+
-
*
/
sqrt()

void main()
{
int relation=0;
double a,b;

cin>>a;

cout<<endl;

switch(c=getchar())
{
case '+':relation=1;break;
case '-':relation=2;break;
case '*':relation=3;break;
case '/':relation=4;break;
}

cout<<endl;

cin>>b;
cout<<endl;

int r;

switch(relation)
{
case 1:r=a+b;break;
case 2:r=a-b;break;
case 3:r=a*b;break;
case 4:r=a/b;break;
}

cout<<r;
}

楼上是C++..我改了一下：
#include <math.h>
void main()
{
int relation=0;
double a,b,r;
printf("Input the Numbers(like:5,20)/n");
scanf("%f,%f",&a,&b);
printf("Choose +:1 -:2 *:3 /:4 sqrt:5/n");
scanf("%d",&relation);
switch(relation)
{
ca