objective-c第七章课后练习3

题：Fraction类对负分数适用吗？例如：1/4-1/2 能否显示成-1/4?

//--------类定义实现参考上篇随笔,此处需更改print方法和main主方法部分----------
- (void) print: (BOOL) yesOrNo//打印
{
    if (yesOrNo == YES) {
        [self reduce];
    }
    
    if (num < 0)
    {
        num = -num;
        NSLog(@"-%i/%i",num,den);
    }
    else
    {
        NSLog(@"%i/%i",num,den);
    }
}

- (Fraction *) subFraction: (Fraction *) f
{
    Fraction *result = [[Fraction alloc]init];
    
    result.num = num * f.den - den * f.num;
    result.den = den * f.den;
    
    //[result reduce];
    
    return result;
    
}


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

int main(int argc, const char * argv[]) {
    @autoreleasepool {
        Fraction *myF = [[Fraction alloc]init];
        Fraction *myF_2 = [[Fraction alloc]init];
        Fraction *myResult;
        
        int i;//接受输入1或0
        BOOL b;//布尔类型判断i的值
        
        [myF setN:1 andSetD:4];
        [myF_2 setN:1 andSetD:2];
        
        NSLog(@"Need to Simple? 1 or 0");//提示输入1或0
        scanf("%i",&i);
        b = i;//将i值传给布尔类型的b判断是否对分数进行约简
        
        myResult = [myF subFraction:myF_2];//减法
        [myResult print:b];
        
        myResult = [myF mulFraction:myF_2];//乘法
        //[myResult print];
        
        myResult = [myF divFraction:myF_2];//除法
        [myResult print:b];
        
        //[myResult print];
        
        
    }
    return 0;
}