object-c如何创建一个简单的类

2023-10-18 21:17 279阅读 0赞

这个实例为我们展示了在object-c中，如何创建和使用类（class），不要忘记，object-c是面向对象的啊。

Fraction,，正如它的含义所在一样，这个程序只提供了打印分数的例子。

**1. 代码：**

//文件名：Fraction.h

\#import <Foundation/NSObject.h>  
  
  
@interface Fraction: NSObject \{  
int numerator;  
int denominator;  
\}  
  
  
\-(void) print;  
\-(void) print2;  
\-(void) setNumerator: (int) d;  
\-(void) setDenominator: (int) d;  
\-(int) getNumerator;  
\-(int) getDenominator;  
@end

//文件名：Fraction.m

\#import "Fraction.h"  
\#import <stdio.h>  
  
  
@implementation Fraction  
\-(void) print \{  
printf( "%i/%i", numerator, denominator );  
\}  
  
  
\-(void) print2 \{  
printf( "%i/%i", \[self getNumerator\], \[self getDenominator\] );  
\}  
  
  
\-(void) setNumerator: (int) n \{  
numerator = n;  
\}  
  
  
\-(void) setDenominator: (int) d \{  
denominator = d;  
\}  
  
  
\-(int) getDenominator \{  
return denominator;  
\}  
  
  
\-(int) getNumerator \{  
return numerator;  
\}  
@end  
  
// main.m

\#import <stdio.h>  
\#import "Fraction.h"  
  
  
int main( int argc, const char \*argv\[\] ) \{  
// create a new instance  
Fraction \*frac = \[\[Fraction alloc\] init\];  
  
  
// set the values  
\[frac setNumerator: 1\];  
\[frac setDenominator: 3\];  
  
  
// print it  
printf( "The fraction is: " );  
\[frac print\];  
printf( "\\n" );  
\[frac print2\];  
printf( "\\n" );  
  
  
// free memory  
\[frac release\];  
  
  
return 0;  
\}

**2.编译运行：**

$ gcc -fconstant-string-class=NSConstantString -c main.m -I /GNUstep/System/Library/Headers

$ gcc -c Fraction.m -I /GNUstep/System/Library/Headers

$ gcc -o main main.o Fraction.o -L /GNUstep/System/Library/Libraries/ -lobjc -lgnustep-base

$ ./main.exe  
The fraction is: 1/3  
1/3

**3. 说明：**

（1）. 请比较print 和print2两个消息的不同;

（2）. 关于Fraction,更复杂的例子请参考“[Windows如何进行Object-C的开发][Windows_Object-C]”一文,位于iPhone目录下。

[Windows_Object-C]: http://blog.csdn.net/liranke/article/details/5810284