Programming Forums > Application Development > C++

sys0p · Nov 25th, 2004, 9:24 AM

Hi all!

I was working with classes, and was trying to test the friend directive. In the code below I keep getting the following error on compilation:

c:\c__~1\new\prac\struct~1\friend.cpp:35: no `int stack::compare(stack, stack)' member function declared in class `stack'

The code is below. I hope someone can help me out?

Cheers

(Toggle Plain Text)

#include <iostream.h>

const int SIZE = 100;

class stack {
	private:
 int count;
 int data[SIZE];

	public:
 void init( void );
 void push( const int item );
 int pop( void );
 friend int compare( const stack &stack1, const stack &stack2 );
};

void stack::init( void )
{
count = 0;
};

void stack::push( const int item )
{
data[count] = item;
++count;
};

int stack::pop( void )
{
--count;
return(data[count]);
};

int stack::compare( const stack stack1, const stack stack2 )
{
if( stack1.count != stack2.count )
return(0);
	for( int i = 0; i < stack1.count; ++i )
	{
	if( stack1.data[i] != stack2.data[i] )
	return(0);
	};
return(1);
};

main()
{
class stack myStack1;
class stack myStack2;

myStack1.push(4);
myStack2.push(3);

cout << compare( myStack1, myStack2 ) << '\n';

return(0);
};

Eggbert · Nov 25th, 2004, 11:06 AM

You have two problems:

>int stack::compare
compare is a friend, not a member. You don't qualify friends as if they were members unless they actually are.

>friend int compare( const stack &stack1, const stack &stack2 );
>int compare( const stack stack1, const stack stack2 )
Notice how the declaration takes references to a const stack and the definition takes const stack objects. These are two different functions and the compiler will treat them as overloads. Change the definition to match the declaration and the code will compile:

(Toggle Plain Text)

class stack {
private:
 int count;
 int data[SIZE];

public:
 void init( void );
 void push( const int item );
 int pop( void );
 friend int compare( const stack &stack1, const stack &stack2 );
};

...

int compare( const stack &stack1, const stack &stack2 )
{
 if( stack1.count != stack2.count )
  return(0);
 for( int i = 0; i < stack1.count; ++i )
 {
  if( stack1.data[i] != stack2.data[i] )
   return(0);
 };
 return(1);
};

sys0p · Nov 25th, 2004, 1:39 PM

Hey!
Oh, Oh, Oh what a stupid mistake to make!!! Thanks for pointing out where I went wrong. At least, know I know where I went wrong

Cheers

Nov 25th, 2004, 9:24 AM	#1
sys0p Programmer Join Date: Oct 2004 Posts: 73 Rep Power: 4	Hi all! I was working with classes, and was trying to test the friend directive. In the code below I keep getting the following error on compilation: c:\c__~1\new\prac\struct~1\friend.cpp:35: no `int stack::compare(stack, stack)' member function declared in class `stack' The code is below. I hope someone can help me out? Cheers (Toggle Plain Text) #include <iostream.h> const int SIZE = 100; class stack { private: int count; int data[SIZE]; public: void init( void ); void push( const int item ); int pop( void ); friend int compare( const stack &stack1, const stack &stack2 ); }; void stack::init( void ) { count = 0; }; void stack::push( const int item ) { data[count] = item; ++count; }; int stack::pop( void ) { --count; return(data[count]); }; int stack::compare( const stack stack1, const stack stack2 ) { if( stack1.count != stack2.count ) return(0); for( int i = 0; i < stack1.count; ++i ) { if( stack1.data[i] != stack2.data[i] ) return(0); }; return(1); }; main() { class stack myStack1; class stack myStack2; myStack1.push(4); myStack2.push(3); cout << compare( myStack1, myStack2 ) << '\n'; return(0); }; #include <iostream.h> const int SIZE = 100; class stack { private: int count; int data[SIZE]; public: void init( void ); void push( const int item ); int pop( void ); friend int compare( const stack &stack1, const stack &stack2 ); }; void stack::init( void ) { count = 0; }; void stack::push( const int item ) { data[count] = item; ++count; }; int stack::pop( void ) { --count; return(data[count]); }; int stack::compare( const stack stack1, const stack stack2 ) { if( stack1.count != stack2.count ) return(0); for( int i = 0; i < stack1.count; ++i ) { if( stack1.data[i] != stack2.data[i] ) return(0); }; return(1); }; main() { class stack myStack1; class stack myStack2; myStack1.push(4); myStack2.push(3); cout << compare( myStack1, myStack2 ) << '\n'; return(0); };

Nov 25th, 2004, 11:06 AM	#2
Eggbert Professional Programmer Join Date: Nov 2004 Posts: 250 Rep Power: 4	You have two problems: >int stack::compare compare is a friend, not a member. You don't qualify friends as if they were members unless they actually are. >friend int compare( const stack &stack1, const stack &stack2 ); >int compare( const stack stack1, const stack stack2 ) Notice how the declaration takes references to a const stack and the definition takes const stack objects. These are two different functions and the compiler will treat them as overloads. Change the definition to match the declaration and the code will compile: (Toggle Plain Text) class stack { private: int count; int data[SIZE]; public: void init( void ); void push( const int item ); int pop( void ); friend int compare( const stack &stack1, const stack &stack2 ); }; ... int compare( const stack &stack1, const stack &stack2 ) { if( stack1.count != stack2.count ) return(0); for( int i = 0; i < stack1.count; ++i ) { if( stack1.data[i] != stack2.data[i] ) return(0); }; return(1); }; class stack { private: int count; int data[SIZE]; public: void init( void ); void push( const int item ); int pop( void ); friend int compare( const stack &stack1, const stack &stack2 ); }; ... int compare( const stack &stack1, const stack &stack2 ) { if( stack1.count != stack2.count ) return(0); for( int i = 0; i < stack1.count; ++i ) { if( stack1.data[i] != stack2.data[i] ) return(0); }; return(1); };

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Nov 25th, 2004, 1:39 PM	#3
sys0p Programmer Join Date: Oct 2004 Posts: 73 Rep Power: 4	Hey! Oh, Oh, Oh what a stupid mistake to make!!! Thanks for pointing out where I went wrong. At least, know I know where I went wrong Cheers

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Programming Forums > Application Development > C++

Problem With Friend Directive