Question

我的目标是编写一个类并仅使用__iter__和next方法来查找数字的除数。这是我写的：

class Divisors(object):
    def __init__(self, integer):
        self.integer = integer
    def __iter__(self):
        self.divisor = 1
        return self
    def next(self):
        div = 0
        if self.divisor >= self.integer:
            raise StopIteration
        else:
            if self.integer % self.divisor == 0:
                div = self.divisor
            self.divisor += 1
        return div

当我查看时：

for i in Divisors(6):
    print i

我得到了

而不是1 2 3 6

但我不确定是否应该使用print而不是上面使用的 div 。关于我在这里做错了什么的提示？

Answer 1

在这种情况下进行调试时，您应该逐行进行操作。您编写的代码不会只打印数字的除数。

如果仔细查看方法- (IBAction)albumView:(id)sender { UIImagePickerController *imagePicker = [[UIImagePickerController alloc] init]; [imagePicker.view setFrame:self.view.frame]; [imagePicker setSourceType:UIImagePickerControllerSourceTypePhotoLibrary]; [imagePicker setDelegate:self]; [ipc presentViewController:imagePicker animated:YES completion:nil]; } - (IBAction)cancel_IPC:(id)sender { [self imagePickerControllerDidCancel:ipc]; } -(void)imagePickerControllerDidCancel:(UIImagePickerController *)picker{ [picker dismissViewControllerAnimated:YES completion:nil]; if(picker.sourceType == UIImagePickerControllerSourceTypeCamera){ LeafsnapTabBarController * tabBarController = (LeafsnapTabBarController*)self.tabBarController; [self.tabBarController setSelectedIndex:tabBarController.previousTabIndex]; } } -(void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info { UIImage* origImage = [info objectForKey:UIImagePickerControllerOriginalImage]; /*do whatever you need to do with the img*/ [picker dismissViewControllerAnimated:YES completion:nil]; /*dismiss the original UIImagePickerController in background */ if(picker.sourceType == UIImagePickerControllerSourceTypePhotoLibrary){ [ipc dismissViewControllerAnimated:YES completion:nil]; } [mLocationManager stopUpdatingLocation]; }，它首先将next初始化为0.然后，如果除数大于或等于整数，则停止循环。否则，如果整数可被除数整除，则修改div然后返回div（修改后的或原始的0）。

遵循上述逻辑，只要整数不能被除数整除，代码就会返回0。循环执行5次后停止（整数= 6）。因此输出div。在前三次迭代中，除数成功地将整数除（divisor = 1,2,3），而在接下来的两次中它没有（divisor = 4和5）。当除数变得等于整数（在这种情况下为6）时，循环停止而不返回任何内容。

这是python2的工作代码，它产生所需的输出

1 2 3 0 0

产生的输出是：

class Divisors(object):
def __init__(self,integer):
    self.integer = integer

def __iter__(self):
    self.divisor = 0
    return self

def next(self):
    div = 0

    self.divisor += 1
    while self.integer >= self.divisor and self.integer % self.divisor != 0:
        self.divisor += 1

    if self.divisor > self.integer:
        raise StopIteration

    div = self.divisor
    return div


for i in Divisors(6):
    print i

Answer 2

您的-方法中需要while循环。我们可以添加它，然后简化您的逻辑：

next()

对python的简单迭代

2 个答案: