return 语句在 python 递归中不返回任何内容 [英] return statement doesnt return anything in python recursion

问题描述

下面的方法在字符串中查找是否有任何 python 方法.

def there_is_a_call( string ):返回 string.find('(') > -1def find_and_remove_functions( string , found_functions ):如果没有 there_is_a_call( string ):打印(找到函数)返回 found_functions别的:function_end = string.find('(')function_string = string[:function_end][::-1]if function_string.find('.') >-1 :index = function_string.find('.')elif function_string.find(' ') >-1:index = function_string.find(' ')别的:索引 = len(function_string) - 1func_name = function_string[ : index + 1 ][::-1] + '()'new_list = found_functionsnew_list.append(func_name)find_and_remove_functions( string[ function_end + 1: ], found_functions )

所以我尝试看看它是否有效，然后发生了这种情况；

<预><代码>>>>>a = find_and_remove_functions( 'func() and some more()' , [] )['func()', '更多()']>>>>打印(一)没有任何

为什么在打印 found_functions 时 return 语句不返回任何内容?

解决方案

这里:

find_and_remove_functions( string[ function_end + 1: ], found_functions )

应该

return find_and_remove_functions( string[ function_end + 1: ], found_functions )

The methods below look in a string to find if it has any python methods.

def there_is_a_call( string ): 
    return string.find('(') > -1

def find_and_remove_functions( string , found_functions ): 
    if not there_is_a_call( string ):
        print( found_functions )
        return found_functions
    else: 
        function_end    = string.find('(')
        function_string = string[:function_end][::-1]
        if function_string.find('.') > -1 : 
            index = function_string.find('.')
        elif function_string.find(' ') > -1: 
            index = function_string.find(' ')
        else:
            index = len(function_string) - 1 
        func_name       = function_string[ : index + 1 ][::-1] + '()'
        new_list = found_functions 
        new_list.append( func_name )
        find_and_remove_functions( string[ function_end + 1: ], found_functions )

So I try to see if it works and then this happens;

>>>> a = find_and_remove_functions( 'func() and some more()' , [] )
['func()', ' more()']
>>>> print(a)
None 

Why is the return statement not returning anything while the found_functions do get printed?

解决方案

Here:

find_and_remove_functions( string[ function_end + 1: ], found_functions )

should be

return find_and_remove_functions( string[ function_end + 1: ], found_functions )

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