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          1. Python next()

            更新:

            內置函數next()用于從迭代器返回下一個元素。通常該函數用在循環中。當它到達迭代器的末尾時,它會拋出一個錯誤。為了避免這種情況,我們可以指定默認值。

             **next(iterator, default)** #where iterable can be list, tuple etc 
            

            下一個()參數:

            接受兩個參數。在這種情況下,迭代器可以是字符串、字節、元組、列表或范圍,集合可以是字典、集合或凍結集合。

            參數 描述 必需/可選
            可迭代的 從迭代器中檢索到下一項 需要
            系統默認值 如果迭代器用盡,則返回該值 可選擇的

            下一個()返回值

            如果它到達迭代器的末尾,并且沒有指定默認值,它將引發 StopIteration 異常。

            | 投入 | 返回值 | | 迭代程序 | 迭代器的下一個元素 |

            Python 中next()方法的示例

            示例 1:如何獲取下一個項目

             random = [5, 9, 'cat']
            
            # converting the list to an iterator
            random_iterator = iter(random)
            print(random_iterator)
            
            # Output: 5
            print(next(random_iterator))
            
            # Output: 9
            print(next(random_iterator))
            
            # Output: 'cat'
            print(next(random_iterator))
            
            # This will raise Error
            # iterator is exhausted
            print(next(random_iterator)) 
            

            輸出:

             <list_iterator at="" object="">5
            9
            cat
            Traceback (most recent call last):
              File "python", line 18, in <module>StopIteration</module></list_iterator> 

            示例 2:將默認值傳遞給下一個()

             random = [5, 9]
            
            # converting the list to an iterator
            random_iterator = iter(random)
            
            # Output: 5
            print(next(random_iterator, '-1'))
            
            # Output: 9
            print(next(random_iterator, '-1'))
            
            # random_iterator is exhausted
            # Output: '-1'
            print(next(random_iterator, '-1'))
            print(next(random_iterator, '-1'))
            print(next(random_iterator, '-1')) 
            

            輸出:

            5
            9
            -1
            -1
            -1 

            示例 3:函數到達集合末尾時拋出一個錯誤

             # Python `next()` function example  
            number = iter([256, 32, 82]) # Creating iterator  
            # Calling function  
            item = next(number)   
            # Displaying result  
            print(item)  
            # second item  
            item = next(number)  
            print(item)  
            # third item  
            item = next(number)  
            print(item)  
            # fourth item  
            item = next(number) # error, no item is present  
            print(item) 
            

            輸出:

            Traceback (most recent call last): 
              File "source_file.py", line 14, in 
                item = next(number)
            StopIteration 
            256
            32
            82 
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