main.cpp

易学c++源码

#include "iostream.h"
int main()
{
	float r;
	float l;
	const float pi=3.1415926F;
	cout <<"请输入半径：";
	cin >>r;
	l=2*pi*r;
	cout <<"这个圆的周长为" <<l <<endl;
	return 0;
}