Chapter 10 Exercise 2

[clouded]

Here's my take on this one, notice the self statements in the methods:

Code: (Objective-C)

// Chapter 10 Exercise 2
// Given that you label the method developed in exercise 1 the designated initializer
// for the Rectangle class, and based on the Square and Rectangle class definitions
// from Chapter 8, add an initializer method to the Square class according to the
// following declaration:
//     -(id) initWithSide: (int) side;

//  main.m

#import <Foundation/Foundation.h>
#import "Rectangle.h"
#import "Square.h"

int main (int argc, char * argv[]) {
    
    @autoreleasepool {
        Rectangle *rect1, *rect2;
        
        rect1 = [[Rectangle alloc] init];
        NSLog (@"Rectangle: w = %i, h = %i", rect1.width, rect1.height); 
        NSLog (@"Area = %i, Perimeter = %i", [rect1 area], [rect1 perimeter]);
        NSLog (@" ");
        
        [rect1 setWidth: 5 andHeight: 8];
        NSLog (@"Rectangle: w = %i, h = %i", rect1.width, rect1.height); 
        NSLog (@"Area = %i, Perimeter = %i", [rect1 area], [rect1 perimeter]);
        NSLog (@" ");
        
        rect2 = [[Rectangle alloc] initWithWidth: 6 andHeight: 9];
        NSLog (@"Rectangle: w = %i, h = %i", rect2.width, rect2.height); 
        NSLog (@"Area = %i, Perimeter = %i", [rect2 area], [rect2 perimeter]);
        NSLog (@" ");

        Square *mySquare = [[Square alloc] initWithSide: 5]; // <-- replaced " init]" with " initWithSide: 5]"
        // [mySquare setSide: 5]; // <-- Commented to omit
        NSLog (@"Square s = %i", [mySquare side]);
        NSLog (@"Area = %i, Perimeter = %i", [mySquare area], [mySquare perimeter]);
    }
    return 0;
}

Code: (Objective-C)

//  Square.h

#import "Rectangle.h"

@interface Square : Rectangle

-(id) initWithSide: (int) side;
-(void) setSide: (int) s; 
-(int) side;
@end

Code: (Objective-C)

//  Square.m

#import "Square.h"

@implementation Square

-(id) initWithSide: (int) side
{
    self = [super init];
    if (self)
        self = [self initWithWidth: side andHeight: side];
    return self;
}
-(void) setSide: (int) s 
{
    [self setWidth: s andHeight: s];
}
-(int) side
{
    return self.width;
}
@end

Code: (Objective-C)

//  Rectangle.h

#import <Foundation/Foundation.h>

@interface Rectangle: NSObject
@property int width, height;

-(id) init;
-(id) initWithWidth: (int) w andHeight: (int) h;
-(void) setWidth: (int) w andHeight: (int) h;
-(int) area;
-(int) perimeter;
@end

Code: (Objective-C)

//  Rectangle.m

#import "Rectangle.h"

@implementation Rectangle
@synthesize width, height;

-(id) init 
{
    self = [super init]; 
    if (self)
        [self setWidth: 1 andHeight: 1];
    return self;
}
-(id) initWithWidth: (int) w andHeight: (int) h
{
    self = [super init];
    if (self)
        [self setWidth: w andHeight: h];
    return self;
}
-(void) setWidth: (int) w andHeight: (int) h
{
    width = w;
    height = h;
}
-(int) area
{
    return width * height;
}
-(int) perimeter
{
    return (width + height) * 2;
}
@end

Output:

Rectangle: w = 1, h = 1
Area = 1, Perimeter = 4

Rectangle: w = 5, h = 8
Area = 40, Perimeter = 26
 
Rectangle: w = 6, h = 9
Area = 54, Perimeter = 30

Square s = 5
Area = 25, Perimeter = 20

[mo7ionsickness]

Code: (Objective-C)

-(id) initWithSide:(int)side
{
    self = [super init];
    
    if (self)
        [self setSide:side];
    
    return self;
}

Code: (Objective-C)

        Square *newSquare = [[Square alloc] initWithSide:15];
        NSLog(@"newSquare side = %i", [newSquare side]);

2012-08-21 12:36:45.132 Rectangle[776:303] newSquare side = 15