第二讲：什么叫做“类”

Sian

Fraction.h

1. #import <Foundation/NSObject.h>
2.   
3. @interface Fraction: NSObject  
4. {
5.     int numerator;  
6.     int denominator;  
7. }  
9. -(void) print;
10. -(void) setNumerator: (int) n;
11. -(void) setDenominator: (int) d;
12. -(int) numerator;
13. -(int) denominator;
14. @end

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Fraction.m

1. #import "Fraction.h"
2. #import <stdio.h>  
3. @implementation Fraction
4. -(void) print
5. {
6.     printf("%i/%i",numerator,denominator);
7. }
8.   
9. -(void) setNumerator: (int) n
10. {   
11.     numerator = n;
12. }
13. -(void) setDenominator: (int) d
14. {   
15.     denominator = d;
16. }
17.   
18. -(int) denominator
19. {   
20.     return denominator;
21. }
22. -(int) numerator
23. {   
24.     return numerator;
25. }
26. @end

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main.m

1. #import <stdio.h>
2. #import "Fraction.h"  
3. int main( int argc, const char *argv[] )
5. {
6. Fraction *frac = [[Fraction alloc] init];
7. [frac setNumerator: 1];  
8. [frac setDenominator: 3];
10. printf( "The fraction is: " );  
11. [frac print];
12. [frac release];
14. return 0;
15. }

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