Please help me look at the code C ++

tongliang

#include <iostream.h>


const float PI = 3.14f;



void main ()
{
class Cricle; // I think something went wrong here
Cricle x;
int r;
cin >> r;
cout << "S's Price is" << x.S_Price (r) << endl;
cout << "C's Price is" << x.C_Price (r) << endl;
}

class Cricle
{
private:
int raidom;
public:
float Get_C (int raidom)
{
return (raidom * PI * 2);
}

float Get_S (int raidom)
{
return (PI * raidom * raidom);
}

float S_Price (int raidom)
{
float Result;
Result = Get_S (raidom) -Get_S (raidom-3);
return (20 * Result);
}

float C_Price (int raidom);
};

float Cricle :: C_Price (int raidom)
{
float Result1;
Result1 = Get_C (raidom);
return (35 * Result1);
}

Always give an error when compiling
D:\Program Files\Microsoft Visual Studio\MyProjects\Cricle\Cricle.cpp (15): error C2228: left of '.C_Price' must have class / struct / union type

D:\Program Files\Microsoft Visual Studio\MyProjects\Cricle\Cricle.cpp (14): error C2228: left of '.S_Price' must have class / struct / union type

D:\Program Files\Microsoft Visual Studio\MyProjects\Cricle\Cricle.cpp (11): error C2065: 'x': undeclared

Please help me see. The class must be written below main ()

jotoos

#include <iostream.h>


const float PI = 3.14f;

class Cricle
{
private:
int raidom;
public:
float Get_C (int raidom)
{
return (raidom * PI * 2);
}

float Get_S (int raidom)
{
return (PI * raidom * raidom);
}

float S_Price (int raidom)
{
float Result;
Result = Get_S (raidom) -Get_S (raidom-3);
return (20 * Result);
}

float C_Price (int raidom);
};


void main ()
{
Cricle x;
int r;
cin >> r;
cout << "S's Price is" << x.S_Price (r) << endl;
cout << "C's Price is" << x.C_Price (r) << endl;
}



float Cricle :: C_Price (int raidom)
{
float Result1;
Result1 = Get_C (raidom);
return (35 * Result1);
}

tongliang

Big Brother

The class must be written under main ()

orangedj

why

lklklk

The main function main should be placed under the class, otherwise it will not recognize the class or variable or function defined under it

zfy010317

There is no necessary connection with the main function.
Mainly c ++ is a language that needs to be declared before use. The class is used in main, but there is no declaration before, which will make the compiler
Puzzled.

starplatinum

When the compiler compiles Circle x, it must know how much memory overhead x is, so if there is no class structure declaration, including the definition of member variables, it cannot be compiled, if you must put the declaration behind, only use pointers.
Circle * x = (Circle *) operator new (4); // This is no problem, because the pointer is always four bytes
But even so, when you use X, you still need to declare the prototype of the class.If you write it all to the back, it is like you define a global variable and use it without adding a declaration in front.

huhuhu_ggg

#include <iostream.h>


const float PI = 3.14f;
class Cricle
{
private:
int raidom;

public:
float Get_C (int raidom)
{
return (raidom * PI * 2);
}
The
float Get_S (int raidom)
{
return (PI * raidom * raidom);
}
The
float S_Price (int raidom)
{
float Result;
Result = Get_S (raidom) -Get_S (raidom-3);
return (20 * Result);
}
float C_Price (int raidom);
};

float Cricle :: C_Price (int raidom)
{
float Result1;
Result1 = Get_C (raidom);
return (35 * Result1);
}
void main ()
{
// class Cricle; // I think something went wrong here
Cricle x;
int r;
cout << "please input r:" << endl;
cin >> r;

cout << "S's Price is" << x.S_Price (r) << endl;
cout << "C's Price is" << x.C_Price (r) << endl;
}

forsysy

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