Why is it saying this...

[NOMADMAN]

I have a class called mouse. I'm tring to use the << friend. In my public section of the class declaration I have:

friend ostream & operator << (ostream & o, const mouse m);

In the cpp for the definitions I have:

ostream & operator << (ostream & o, const mouse m)
{
     // PRINT MOUSE
     o << "M";

     return o;
}

Then I get the error: binary '<<' : no operator defined which takes a right-hand operand of type 'class mouse' (or there is no acceptable conversion)

I'm not sure if you put friend in from of the word ostream but when I tried I got 3 errors, including the first:
'<<' : a friend function can only be declared in a class
'<<' : 'void' function returning a value

Anyone know whats going wrong? If you want I'll post the code, don't think its really nessicary seeing as I'm probably just missing something.

NOMAD

[Pales]

hmm wondering too

[NOMADMAN]

I'll post the code for the mouse.h and mouse.cpp, also I have uploaded a zip with mouse.h, mouse.cpp, and main.cpp. assume maze works (cause it does).

#include <iostream>
using std:: ostream;
using std::endl;

#include "maze.h"
//#include "screen.h"

class mouse
{
protected:
    unsigned short x;
    unsigned short y;
    unsigned int steps;
    // N = 1; E = 2; S = 3; W = 4;
    unsigned int direction;
    char footprint;
    bool righthand;

    void turnLeft();
    void turnRight();
    void stepForward();

public:
    mouse(maze<char> m, char charfoot);
    void takeOneStep(maze<char> m);
    bool AmIInTheExit(maze<char> m, unsigned short x, unsigned short y);
    bool AmIInTheEntrance(maze<char> m, unsigned short x, unsigned short y);
    //friend ostream & operator << (ostream & o, const mouse m);
    friend ostream & operator << (ostream & o, const mouse m);

}; 

Above is mouse.h

#include "mouse.h"

mouse::mouse(maze<char> m, char charfoot)
{    
    m.getEntrance(x, y);
    
    steps = 0;
    // N = 1; E = 2; S = 3; W = 4;
    direction = 2;
    footprint = charfoot;
    righthand = true;
}

void mouse::turnLeft()
{
    direction--;
    if (direction < 1)
        direction = 4;
}

void mouse::turnRight()
{
    direction++;
    if (direction > 4)
        direction = 1;
}

void mouse::stepForward()
{

}

void mouse::takeOneStep(maze<char> m)
{
    //What's the difference between this and stepForward()?
    switch (direction)
    {
    case 1:
        
        if ( !( m.IsThisCellBlocked(x, ( y-1 )) ) )
            y--;
        break;
    case 2:
        if ( !( m.IsThisCellBlocked(( x+1 ), y-1) ) )
            x++;
        break;
    case 3:
        if ( !( m.IsThisCellBlocked(x, ( y+1 )) ) )
            y++;
        break;
    case 4:
        if ( !( m.IsThisCellBlocked(( x-1 ), y-1) ) )
            x--;
        break;
    default:
        break;
    }
}

bool mouse::AmIInTheExit(maze<char> m, unsigned short x, unsigned short y)
{
    return m.IsThisCellTheExit (x, y);
}

bool mouse::AmIInTheEntrance(maze<char> m, unsigned short x, unsigned short y)
{
    return m.IsThisCellTheEntrance (x, y);
}

ostream & operator << (ostream & o, const mouse m)
{

    //Clear screen and set
    //CURSOR AT TOP LEFT!!!
    //ClearScreen();

    // PRINT MOUSE
    cout << "M";

    return o;
}

//End mouse.cpp 

Above is mouse.cpp

Anyway, hope someone can help cause I'm stumped. I just have a feeling its something stupid so keep your eyes open!

NOMAD

[Zaei]

I sliced out everything that had to do with the maze class, and simply compiled your mouse.cpp and .h with a skeleton main function, and there were no errors (gcc under Linux).

Actually, I just figured out what your problem is =). Its this line:

cout << "M";

cout isnt defined, because you dont import it from the std namespace. Either #include <iostream.h> instead of #include <iostream> or add:

using std::cout;

to the top of the mouse.h file.

It compiled for me because I always use iostream.h, which imports the std namespace.

Z.

[NOMADMAN]

I'm sorry, i don't understand you mean:
#include <iostream>
using namespace std;
???

Also, I should have made the cout o right
o << "M";

I'm sorry I'm being so dense. You think you could post the mouse.cpp you got to work?

Thanks once again Z!

NOMAD

[Zaei]

Just remove anything that has to do with maze, and change your include to #include <iostream.h>

Z.

[parksie]

Originally posted by Zaei
Just remove anything that has to do with maze, and change your include to #include <iostream.h>

Z.

Not a good idea.

Not all library vendors have iostream.h importing the new iostreams into the global namespace. In many, it's actually implemented separately.

Therefore, never use iostream.h

[Zaei]

Ok =).

Z.

[NOMADMAN]

I fixed it! Well rather than fixing it I compromised. I turned mouse into a template class and al seems well. Go figure! I tried what you said Z and it worked (compiled) but when I added the maze stuff back it reverted back t how it was. I guess something from maze, maybe its friend ostream, did something.

Anyway, I'm happy it works now!!! Thanks Z and everyone else who have helped me!

NOMAD!