Exercise 11.5

[tknp]

I believe this is the way it was intended to be done.

Rectangle.m

Code: (Objective-C)

#import "Rectangle.h"

@implementation Rectangle

@synthesize width, height;

-(void) setWidth: (int) w andHeight: (int) h
{
    width = w;
    height = h;
}

-(int) area
{
    return width * height;
}

-(int) perimeter
{
    return (width + height) * 2;
}

@end

Square.m

Code: (Objective-C)

#import "Square.h"
#import "Rectangle.h"

@implementation Square

Rectangle *rect;

@synthesize side;

-(Square *) initWithSide: (int) s
{	
	self = [super init];
	
	if (self)
		rect = [[Rectangle alloc] init];
		[rect setWidth: s andHeight: s];
		[self setSide: s];
	
	return self;
}
-(void) setSide: (int) s
{
	side = s;
}

-(int) area
{
	return [rect area];
}
-(int) perimeter
{
	return [rect perimeter];
}

@end

main.m

Code: (Objective-C)

#import "Square.h"

int main (int argc, const char * argv[]) {
    NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];

	Square *a = [[Square alloc] initWithSide: 10];
	
	NSLog(@"Side is: %i", a.side);
	NSLog(@"Area is: %i", a.area);
	NSLog(@"Perimeter is: %i", a.perimeter);
	
    [pool drain];
    return 0;
}

[BombermanX]

Hi tknp,
I noticed you have a 'side' iVar as well as a separate 'rect.width' and 'rect.height'. This means if you change 'side' iVar again, the area and perimeter calculations for your square won't match up.

[m.sniper]

I have the followings:

Square.m

Code: (Objective-C)

#import "Square.h"

@implementation Square

-(Square *) initWithSide: (int) s
{
    self = [self init];
    if (self)
    {
        rect = [[Rectangle alloc] init ];
        [self setSide: s];
    } 
        return self;
}

-(void) setSide: (int) s{
    [rect setWidth: s andHeight:s];
}
-(int) area
{
    return [rect area];
}
-(int) side
{
    return [rect width];
}
-(int) perimeter
{
    return [rect perimeter];
}

@end

[elkie13]

Well, here's how I got it to work.  I don't really understand this question.  I guess we were supposed to use rect as the variable.  All the methods for rect will work with square,  and if you have them written not to change the original, I don't really see how this helps.  I think I must really be missing something from this chapter.


#import "Square.h"

@implementation Square


{

    Rectangle *rect;

}
-(Square *) initWithSide:(int)s
{
    self= [self init];
    if (self)
    {
        rect = [[Rectangle alloc]init];
        [rect setwidth:s andHeight:s];
        [self setside:s];
       
    }
    return self;

}
-(void) setside:(int)s
{
    [rect setwidth:s andHeight:s];
}

     
-(int) side
{
    return [rect width];
}
-(int) area;
{
    return [rect area];
}
-(int) perimeter
{
    return [rect perimeter];
}

@end