LHF Objective-C语法（5）异常处理

最新推荐文章于 2016-11-28 15:57:00 发布

转载最新推荐文章于 2016-11-28 15:57:00 发布 · 442 阅读

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#interface

本文介绍了一个Objective-C中自定义异常DenominatorNotZeroException的实现，用于处理分数类Fraction中分母为0的情况。通过异常抛出和捕获机制确保了程序的健壮性。

分母为0的情况，异常机制来处理

//==============================================
DenominatorNotZeroException.h

#import <Foundation/Foundation.h>
@interface DenominatorNotZeroException :NSException
@end
//==============================================
DenominatorNotZeroException.m

#import "DenominatorNotZeroException.h"
@implementation DenominatorNotZeroException
@end
//==============================================

//改写Fraction.m
-(void)setDenominator:(int)d{
	if(d==0){
		NSException e* = [DenominatorNotZeroException
			exceptionWithName:@"DenominatorNotZeroException"
				   reason:@"The denominator is not 0!"
				 userInfo:nil];
		@throw e;
	}
	denominator = d;
}

-(void)setNumerator:(int)n andDenominator:(int) d{
	if(d==0){
		NSException e* = [DenominatorNotZeroException
			exceptionWithName:@"DenominatorNotZeroException"
				   reason:@"The denominator is not 0!"
				 userInfo:nil];
		@throw e;
	}
	numerator = n;

main方法

int main(int argc,const char * argv[]){
	@try{
		Fraction *frac = [[Fraction alloc] initWithNumerator:3 andDenominator:0];
	}@catch(DenominatorNotZeroException *dne){
		NSLog(@"%s\n",[[dne reason] cString]);
	}@catch(NSException *e){
		NSLog(@"%s\n",[[e name] cString]);
	}@finally{
		NSLog(@"finally run");	
	}
}