10.5

题目一：简单输出

#include<stdio.h>

int main()

{
    printf("hello Qingdao!");
    return 0;
}

题目二：计算圆的面积

#include<stdio.h>

#define PI 3.14

double calculateSquare(int radius);

int main()

{
    int cRadius=0;
    double square=0.0;
    printf("请输入圆的半径:\n");
    scanf("%d",&cRadius);
    square=calculateSquare(cRadius);
    printf("圆的面积是；%f\n",square);
    return 0;
} 
double calculateSquare(int radius)
{
    double result=PI*radius*radius;
    return result;
}