#include<iostream>using namespace std;const double PI=3.14159265358979;//内联函数，根据圆的半径计算其面积；inline double calArea(double radius){return PI*radius*radius;}int main(){double r=3.0;//调用内联函数求圆的面积，编译时此处被替换为CalAre函数体语句double arae=calArea(r);cout<<arae<<endl;return 0;}