Class has no member speak? [closed] - c++

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I am just starting to learn about classes and i am trying to make a very simple code called cat.
In my main, h, and cpp file it says the class "Cat" has no member "speak" looked for a possible solution for awhile now but cant find anything to help.
If i put void Cat::speak() in my h file it corrects the other two, but then it says "Qualified name is not allowed in member deceleration"
//Main
#include <iostream>
#include "Cat.h"
using namespace std;
int main() {
Cat jim;
jim.speak(); //CLASS "CAT" HAS NO MEMBER "SPEAK"
return 0;
}
//cat.h
#pragma once
#ifndef CAT_H_
#define CAT_H_
class Cat {
public:
void::speak(); //THE GLOBAL SCOPE HAS NO SPEAK
};
#endif /*CAT_H_*/
//cat.cpp
#include <iostream>
#include "Cat.h"
using namespace std;
void Cat::speak() { //CLASS "CAT" HAS NO MEMBER "SPEAK"
cout << "Meow!" << endl;
}

Answer 1

void::speak(); //THE GLOBAL SCOPE HAS NO SPEAK
It's interpreting this as void ::speak() where leading an identifier (a name) with :: indicates to C++, "Look in the global scope of all names". :: is the "scope resolution operator"
In the header file, you should just use void speak(); since C++ sees it inside your class declaration and hence knows it's part of the class.

Answer 2

How did it even try to compile this line: void::speak();?
What did you even mean by it? Method speak() inside void namespace? but void is a reserved typename. Moreover, why is it inside the class then?
As I can guess, you were trying to use void speak(); instead.

Answer 3

void::speak()
I figured I would chime in on this answer. But the above line is your problem. Essentially, what you have asked the program to do is look in the scope of the void namespace. However, void is a reserved typename and to my knowledge, does not have a function named speak() in it.
This is the one of the problems with using namespace std. Usually, when you are using something from the standard library, take string for example, you will say, "I need to declare a string here, from the standard library. std::string hello, is a perfectly good example that states, "string belongs in the standard libraries scope." using namespace std is bad practice and you go fumbling around trying things like void::speak() which again, is asking to grab it from void's namespace.
That being said, in classes, the header file is commonly used to declare functions in which you will use later. In the cpp file, you are simply saying, I have a class Cat and from the scope of Cat I will be using the function speak(). So speak() belongs to the class Cat and is in the scope of Cat. Which is why in the cpp file, you call void Cat::speak();
So in summary, you header file should be:
class Cat
{
public:
void speak(); // the class has a public function named speak.
};