Python 谁能给我解释一下这个功能吗 我写了这个函数，但是。。。

当我传入该列表中的名称时，它返回该名称的索引，但当我传入错误的名称时，它返回-1，并且不返回“return（index）”，即使“return（index）”语句不在for循环中，为什么？？而且我不能在“else”语句中添加任何其他内容，我试图在“else”语句中添加一个“print”语句，但它没有打印它

names=['neno', 'jay', 'james,'alex','adam','robert','geen']

name_index=look_up(names,"geen")

print(name_index)


print("the name is at location: {}".format(name_index))

但是，您可以找到具有

名称的函数索引。索引（“名称”）

有关更多信息，您可以实现以下函数：

def look_up_new(search_in, search_this):
    if search_this in search_in:
        return search_in.index(search_this) # returns index of the string if exist
    else:
        print("NOT EXIST") # you can print this line in else block also where I have written False
        return False

names=['neno', 'jay', 'james','alex','adam','robert','geen']

name_index = look_up_new(names, "alex")

if name_index:
    print("the name is at location: {}".format(name_index))
else:
    pass # if you are not willing to doing anything at here you can avoid this loop

---

'james

应该是

'james'

对吗？您编写了一个函数，但不了解它的功能？您是否尝试过使用调试器或纸笔单步执行代码？请澄清您的目标和问题我的问题是，如果您给函数传递了一个错误的名称，那么底部的“return（index）”语句不会运行，为什么它在for循环之外？？

def look_up(to_search,target):
    for (index , item) in enumerate(to_search):
        if item == target:
             break # break statement here will break flow of for loop 
        else:
            return(-1)  # when you write return statement in function function will not execute any line after it

    return(index)
    print("This line never be printed")  # this line is below return statement which will never execute

def look_up_new(search_in, search_this):
    if search_this in search_in:
        return search_in.index(search_this) # returns index of the string if exist
    else:
        print("NOT EXIST") # you can print this line in else block also where I have written False
        return False

names=['neno', 'jay', 'james','alex','adam','robert','geen']

name_index = look_up_new(names, "alex")

if name_index:
    print("the name is at location: {}".format(name_index))
else:
    pass # if you are not willing to doing anything at here you can avoid this loop