Objective-C：除数为0的情况下异常的处理(检测、抛出、捕捉、处理)

 //  DivTest.h
 //  异常的处理
 //
 //  Created by ma c on 15/8/11.
 //  Copyright (c) 2015年. All rights reserved.
 //
 
 #import <Foundation/Foundation.h>
 
 @interface DivTest : NSObject
 @property(nonatomic,assign)CGFloat x;
 @property(nonatomic,assign)CGFloat y;
 @property(nonatomic,assign)CGFloat div;
 -(id)initWithX:(CGFloat) m andY:(CGFloat) n;
 -(void)print;
 @end

// 上面为类的声明部分

//类的实现部分

 //  DivTest.m
 //  异常的处理
 //
 //  Created by ma c on 15/8/11.
 //  Copyright (c) 2015年. All rights reserved.
 //
 
 #import "DivTest.h"
 #import "MyException.h"
 @implementation DivTest
 -(id)initWithX:(CGFloat) m andY:(CGFloat) n
 {
     MyException *me;
     self = [super init];
     if(self!=nil)
     {
         _x = m;
         _y = n;
         if(_y==)
         {//如果_y=0,说明除数为零了,抛出异常给调用者去处理
           @throw  me = [[MyException alloc]initWithName:@"MyException:" reason:@"除数为零了" userInfo:nil];
         }
     }
     return self;
 }
 -(void)print
 {
     NSLog(@"div:%.2f",_x/_y);
 }
 @end

//异常的声明和定义部分

 //  MyException.h
 //  异常的处理
 //
 //  Created by ma c on 15/8/11.
 //  Copyright (c) 2015年. All rights reserved.
 //
 
 #import <Foundation/Foundation.h>
 
 @interface MyException : NSException
 
 @end
 
 //  MyException.m
 //  异常的处理
 //
 //  Created by ma c on 15/8/11.
 //  Copyright (c) 2015年 bjsxt. All rights reserved.
 //
 
 #import "MyException.h"
 
 @implementation MyException
 
 @end

//主函数中对异常的测试和处理

 //  main.m
 //  异常的处理
 //
 //  Created by ma c on 15/8/11.
 //  Copyright (c) 2015年. All rights reserved.
 //
 
 #import <Foundation/Foundation.h>
 #import "DivTest.h"
 #import "MyException.h"
 int main(int argc, const char * argv[])
 {
     @autoreleasepool
     {
         DivTest *dt;
         @try
         {   //检测除数为0的异常
             dt = [[DivTest alloc]initWithX: andY:];
         }
         @catch(MyException *e)
         {   //捕捉除数为零的异常
             NSLog(@"MyException:%@",[e reason]);
         }
         @catch(NSException *e)
         {  //捕捉其他的异常
             NSLog(@"Exception:%@",[e reason]);
         }
         @finally
         {  //一定要执行的代码块
             [dt print];
         }
     }
     return ;
 }