题目1：简单输出

#include<stdio.h>
int main ()
{
   printf("我爱学习");
   return 0;
}

题目2：求圆的表面积

#include<stdio.h>
#define PI 3.14
double calculateArea (int radius);
int main ()
{
  int cRadius =0;
  double Area =0.0;
  printf("请输入圆的半径:\n");
  scanf("%d",&cRadius);
  Area=calculateArea(cRadius);
  printf("圆的面积是:%f\n",Area);
  return 0;
}
  double calculateArea (int radius)
{
  double result = PI*radius*radius;
  return result;
}