求高手帮忙解答一下c++的问题，我不知道哪里有问题？

Question

//rectangular.h
#include
class rectangular
{public:
rectangular(float a=3,float b=4,float c=5);
void in_output();
private:
float length,width,height,volume;
};
rectangular::rectangular(float a,float b,float c)
{
length=a;
width=b;
height=c;
}
//rectangular.cpp

#include"rectangular.h"
void rectangular::in_output()
{
cout<<"请分别输入长方柱的长宽高："< cin>>length>>width>>height;
volume=length*width*height;
cout<<"体积："<<volume<<endl;
}
//file.cpp

#include"rectangular.h"
int main()
{
rectangular v1;
rectangular V2(6);
rectangular V3(7,8);
rectangular V4(9,10,11);
cout<<"第一个体积："<<endl;
v1.in_output();
cout<<"第二个体积："<<endl;
v2(6).in_output(6);
cout<<"第三个体积："<<endl;
v3(7,8).in_output(7,8);
cout<<"第四个体积："<<endl;
v4(9,10,11).in_output(9,10,11);
return 0;
}

报错：
file2.cpp
D:\file2.cpp(11) : error C2065: 'v2' : undeclared identifier
D:\file2.cpp(11) : error C2228: left of '.in_output' must have class/struct/union
type
D:\file2.cpp(13) : error C2065: 'v3' : undeclared identifier
D:\file2.cpp(13) : error C2228: left of '.in_output' must have class/struct/union
type
D:\file2.cpp(15) : error C2065: 'v4' : undeclared identifier
D:\file2.cpp(15) : error C2228: left of '.in_output' must have class/struct/union
type
执行 cl.exe 时出错.

file2.obj - 1 error(s), 0 warning(s)

Answer 1

rectangular v1;
rectangular v2(6);
rectangular v3(7,8);
rectangular v4(9,10,11);

看错误提示，undeclared identifier ， 没有声明的标识符。所以定位到变量。

v2到v4首字母统一小写，你后面用的变量都是小写。