C++ "Variable not declared in this scope" - again

Question

I guess this is a really simple question and, probably, one that has been answered several times over. However, I really do suck at C++ and have searched to no avail for a solution. I would really appreciate the help.

Basically:

#ifndef ANIMAL_H
#define ANIMAL_H

class Animal 
{
 public:
  void execute();
  void setName(char*);
  Animal();
  virtual ~Animal(); 

 private:
  void eat();
  virtual void sleep() = 0;

 protected:
  char* name;
};

class Lion: public Animal 
{
 public:
  Lion();

 private:
  virtual void sleep();
};



class Pig: public Animal 
{
 public:
  Pig();

 private:
  virtual void sleep();
};



class Cow: public Animal
{
 public:
  Cow();

 private:

  virtual void sleep();
};

#endif

Is the header file, where:

#include <iostream>
#include "Animal.h"

using namespace std;

Animal::Animal()
{
 name = new char[20];
}
Animal::~Animal()
{
 delete [] name;
}

void setName( char* _name )
{
 name = _name;
}

void Animal::eat() 
{
 cout << name << ": eats food" << endl;
}
void Animal::execute() 
{
 eat();
 sleep();
}


Lion::Lion()
{
 name = new char[20];
}  
void Lion::sleep()
{
 cout << "Lion: sleeps tonight" << endl;
}


Pig::Pig()
{
 name = new char[20];
}   
void Pig::sleep()
{
 cout << "Pig: sleeps anytime, anywhere" << endl;
}


Cow::Cow()
{
 name = new char[20];
}
void Cow::sleep()
{
 cout << "Cow: sleeps when not eating" << endl;
}

is the C file. As you can see, really simple stuff, but, I get the: "error: ‘name’ was not declared in this scope" whenever I try to compile.

It compiles if I comment out the setName method. Iv tried setting 'name' to public and still get the same error. I have also tried using "this->name = _name" in setName(), which results in "invalid use of ‘this’ in non-member function".

I don't know what else to search for. Thanks in advance.

Answer 1

void setName( char* _name )
{
 name = _name;
}

should be

void Animal::setName( char* _name )
{
  this->name = _name;
}

You need to have Animal:: if you use the this parameter. Without Animal:: it thinks you are just creating a new global function called setName

Answer 2

The hint was "non-member function".

You need to make the function into a member function:

void Animal::setName( char* _name )
{
 name = _name;
}

Answer 3

The way you have written the code setName is a free function, not a member function. For this reason the compiler can't resolve name.

You'll have to change setName to this:

void Animal::setName( char* _name )
{
  name = _name;
}

Answer 4

"It compiles if I comment out the setName method"

You don't have a "setName method" in your program (referring to the problematic definition). You defined a completely independent global function called setName, which is not a "method" of anything. If you want to define a method, i.e. a member function of a class, you have to refer to it using the class_name::method_name format. That would be Animal::setName in your case.