#include <iostream.h>
const double PI=3.1416;     //聲明常量(const變量)PI為3.1416
main() 
{
    //聲明3個(gè)變量
    double r=3,l,s;   

    //計(jì)算圓的周長(zhǎng)
    l=2*PI*r; 
    cout<<"l="<<l<<endl; 
	 
    //計(jì)算圓的面積
    s=PI*r*r; 
    cout<<"s="<<s<<endl;    

    //驗(yàn)證賦值誤差
    int il,is;
    il=l;
    is=s;
    cout<<"il="<<il<<endl; 
    cout<<"is="<<is<<endl;    
}