OOP Chapter 7 : More on Classes

Object-Oriented Programming Language
Chapter 7 : More on Classes

Atit Patumvan
Faculty of Management and Information Sciences
Naresuan University

วันจันทร์ท่ี 26 มีนาคม 12

2

Separate Interface and Implementation ﬁles

Single Source File Separate Source File
SourceCode_A.m SourceCode_A.h

Interface Code Interface Code

SourceCode_A.m
Implementation Code
Implementation Code

Program Code
SourceCode_B.m

Program Code

Atit Patumvan, Faculty of Management and Information Sciences, Naresuan University Object-Oriented Programming Language


3

Separate Interface and Implementation ﬁles

Fraction.h

#import <Foundation/Foundation.h>

@interface Fraction : NSObject
:
@end

Fraction.m
#import "Fraction.h"

@implementation Fraction
:
@end

main.m
#import <Foundation/Foundation.h>
#import "Fraction.h"

int main (int argc, const char * argv[]){ ...


4

Separate Interface and Implementation Files

Program 7.1 main.m
01: #import <Foundation/Foundation.h>
02: #import "Fraction.h"
03:
04: int main (int argc, char * argv[])
05: {
06:! NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];
07:! Fraction * myFraction = [[Fraction alloc] init];
08:
09:! [myFraction setNumerator: 1];
10:! [myFraction setDenominator: 3];
11:
12:! // display the fraction
13:
14:! NSLog (@"The value of myFraction is:");
15:! [myFraction print];
16:! [myFraction release];
17:
18:! [pool drain];
19:! return 0;
20: }



5


Program 7.1 Fraction.h

02:
03: // The Fraction class
04:
05: @interface Fraction : NSObject
06: {
07:! int ! numerator;
08:! int ! denominator;
09: }
10:
11: -(void) print;
12: -(void) setNumerator: (int) n;
13: -(void) setDenominator: (int) d;
14: -(int)!numerator;
15: -(int)!denominator;
16: -(double) convertToNum;
17:
18: @end



6


Program 7.1 Fraction.m
01: #import "Fraction.h" 25: -(double) convertToNum
02: 26: {
03: @implementation Fraction 27:! if(denominator != 0)
04: 28:! ! return (double) numerator / denominator;
05: -(void) print 29:! else
06: { 30:! ! return NAN;
07:! NSLog(@"%i/%i", numerator, denominator); 31: }
08: } 32: @end
09: -(void) setNumerator: (int) n
10: {
11:! numerator = n;
12: }
13: -(void) setDenominator: (int) d
14: {
15:! denominator = d;
16: }
17: -(int)!
numerator
18: {
19:! return numerator;
20: }
21: -(int)!
denominator
22: {
23:! return denominator;
24: }



7

Compiling Program from the Command line

gcc -framwork Foundation Fraction.m main.m -o main

Using GNUMakeﬁle
01: include $(GNUSTEP_MAKEFILES)/common.make
02:
03: TOOL_NAME = main
04: main_HEADERS = Fraction.h
05: main_OBJC_FILES = main.m Fraction.m
06: main_RESOURCE_FILES =
07:
08: include $(GNUSTEP_MAKEFILES)/tool.make



8

Synthesize Accessor Methods

Program 7.1b Fraction.h Program 7.1b Fraction.m
01: #import <Foundation/Foundation.h> 01: #import "Fraction.h"
02: 02:
03: // The Fraction class 03: @implementation Fraction
04: 04:
05: @interface Fraction : NSObject 05: @synthesize numerator, denominator;
06: { 06:
07:! int ! numerator; 07: -(void) print
08:! int ! denominator; 08: {
09: } 09:! NSLog(@"%i/%i", numerator, denominator);
10: 10: }
11: @property int numerator, denominator; 11: -(double) convertToNum
12: 12: {
13: -(void) print; 13:! if(denominator != 0)
14: -(void) convertToNum; 14:! ! return (double) numerator / denominator;
15: 15:! else
16: @end 16:! ! return NAN;
17: }
18: @end



9

Accessing Properties Using Dot Operator

Dot Operator
[myFraction numerator] myFraction.numerator

instance property instance property

[myFraction setNumerator: 3] myFraction.numerator = 3



10

Accessing Properties Using Dot Operator

Program 7.1c main.m
03:
05: {
07:! Fraction * myFraction = [[Fraction alloc] init];
08:
09:! //[myFraction setNumerator: 1];
10:! myFraction.numerator = 1;
11:! //[myFraction setDenominator: 3];
12:! myFraction.denominator = 3;
13:! // display the fraction
14:
15:! NSLog (@"The value of myFraction is:");
16:! [myFraction print];
17:! [myFraction release];
18:
19:! [pool drain];
20:! return 0;
21: }



11

Multiple Argument to Methods

[myFraction setNumerator: 1];
[myFraction setDenominator: 3];

[myFraction setNumerator: 1 andDenominator: 3];

[myFraction setTo: 1 over: 3];



12


02:
03: // The Fraction class
04:
05: @interface Fraction : NSObject
06: {
07:! int ! numerator;
08:! int ! denominator;
09: }
10:
11: @property int numerator, denominator;
12:
13: -(void) print;
14: -(void) setTo: (int) n over: (int) d;
15: -(double) convertToNum;
16:
17: @end



13


Program 7.2 Fraction.m Program 7.2 main.m
01: #import "Fraction.h" 01: import <Foundation/Foundation.h>
02: 02: #import "Fraction.h"
03: @implementation Fraction 03:
04: 04: int main (int argc, char * argv[])
05: @synthesize numerator, denominator; 05: {
06: 06:! NSAutoreleasePool * pool =
07: -(void) print [[NSAutoreleasePool alloc] init];
08: { 07:! Fraction * aFraction =
09:! NSLog(@"%i/%i", numerator, denominator); [[Fraction alloc] init];
10: } 08:
11: -(double) convertToNum 09:! [aFraction setTo: 100 over: 200];
12: { 10:! [aFraction print];
13:! if(denominator != 0) 11:
14:! ! return (double) numerator / denominator; 12:! [aFraction setTo: 1 over: 3];
15:! else 13:! [aFraction print];
16:! ! return NAN; 14:
17: } 15:! aFraction.setNumerator= 1;
18: -(void) setTo: (int) n over: (int) d 16:! aFraction.setDenominator= 7;
19: { 17:! [aFraction print];
20:! numerator = n; 18:
21:! denominator = d;! 19:! [aFraction release];
22: } 20:
23: @end 21:! [pool drain];
22:! return 0;
23: }


14

Operations on Fractions

_ 4 6
1 _ _
+ =
1 4 8
:
16: -(void) add: (Fraction * ) f;
:

:
21: -(void) add: (Fraction * ) f
22: {
23:! numerator = numerator * f.denominator + denominator * f.numerator;
24:! denominator = denominator * f.denominator;
25:
26: }
:



15

Operations on Fractions

Program 7.3 main.m
03:
05: {
07:! Fraction * aFraction = [[Fraction alloc] init];
08:! Fraction * bFraction = [[Fraction alloc] init];
09:
10:! [aFraction setTo: 1 over: 4];
11:! [bFraction setTo: 1 over: 2];
12:
13:! [aFraction print];
14:! NSLog(@"+");
15:! [bFraction print];
16:! NSLog(@"=");
17:
18:! [aFraction add: bFraction];
20:! [aFraction release];
21:! [bFraction release];
22:
23: ! return 0;
24: }



16

Local Variables

Program 7.4 Fraction.m
:
21: -(void) reduce
22: {
23:! int u = numerator;
24:! int v = denominator;
25:! int temp;
26:!
27:! while ( v != 0 ){
28:! ! temp = u % v;
29:! ! u = v;
30:! ! v = temp;
31:! }
32:! numerator /= u;
33:! denominator /= u;
34: }
:



17

Local Variables

Program 7.4 main.m
03:
05: {
09:
12:
14:! NSLog(@"+");
16:! NSLog(@"=");
17:
18:! [aFraction add: bFraction];
19:! [aFraction reduce];
20:
24: ! return 0;
25: }


18

The self Keyword

[self reduce;]

Program 7.4a Fraction.m
:
22: {
25:
26: [self reduce];
26: }
:



19

The static Keyword

-(int) showPage
{
static int pageCount = 0;
:
++pageCount;
:
return pageCount;
}

#import “Printer.h”
static int pageCount;

@implementation Printer
:
@end



20

Allocating and Return Objects from Methods

:
16: -(Fraction) add: (Fraction * ) f;
:

:
22: {
25:
26: [self reduce];
26: }
:



21


Program 7.5 main.m
03:
05: {
09:
12:
14:! NSLog(@"+");
16:! NSLog(@"=");
17:
18:! [[aFraction add: bFraction] print];
19:
22:! [pool drain];
23:! return 0;
24: }



22


Program 7.6 main.m
03:
05: {
08:! Fraction * sum = [[Fraction alloc] init], * sum2;
09:
10:! int i, n, pow2;
11:
12:! [sum setTo: 0 over: 1];
13:
14:! NSLog(@"Enter you value for n:" );
15:! scanf("%i", &n);
16:!
17:! pow2 = 2;
18:! for(i = 1; i<=n; ++i){
19:! ! [aFraction setTo: 1 over: pow2];
20:! ! sum2 = [sum add: aFraction];
21:! ! [sum release];
22:! ! sum = sum2;
23:! ! pow2 *= 2;
24:! }
25:!


23


Program 7.6 main.m
26:! NSLog(@"After %i iterations, the sum is %g", n , [sum convertToNum]);
27:
29:! [sum release];
30:!
31:! [pool drain];
32:! return 0;
33: }

2012-03-26 11:07:12.238 main[3496] Enter you value for n:
5
2012-03-26 11:07:14.261 main[3496] After 5 iterations, the sum is 0.96875

10

15



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