#include <iostream.h>

#include <iostream.h>
#include <math.h>
void main()
{
double radius,height;
cout <<"请输入圆柱体的半径和高: \n";
cin >>radius >> height;
double volume=radius * radius * height *'M_PI';
cout <<"该圆柱体的体积为:"<<volume<<endl;
cout<<"\n请输入球半径:\n";
cin >> radius;
double areaofsphere=4 * radius * radius *M_PI;
cout <<"该球面面积为:"<<areaofsphere<<endl;
double length,width;
cout<<"\n请输入长方体的长.宽.高;\n";
cin >>length>>width>>height;
volume=length * width * height;
cout <<"该长方体的体积为:"<<volume<<endl;
}
运行结果:k.cpp(12) : error C2065: 'M_PI' : undeclared identifier

#include <iostream> #include<iostream.h 关于 #include<> #include<vector> #include<algorithm>是什么意思啊？ #include<stdio.h> #include<format.h> #include <graphics.h> C++的#include<> #include <iostream.h> #include<windows.h>