python NameError:名称"xxx"未定义 [英] python NameError: name 'xxx' is not defined

问题描述

puzzle = [[' 1', ' 2', ' 3', ' 4'], [' 5', ' 6', ' 7', ' 8'],[ ' 9', '10', '11', '12'], ['13', '14', '15', ' X']]

def find_pos(alist, item):
    for i in alist:
        for j in range(4):
            if i[j] == item:
                row = alist.index(i)
                col = j

find_pos(puzzle,' X')

a = row
print(a)

我想我通过运行函数find_pos定义了名称row，如果没有，该如何解决以获取row

I think I defined the name row by running the function find_pos, if not, how to fix it to get row

请勿在find_pos函数

推荐答案

只需从函数中返回值:

puzzle = [[' 1', ' 2', ' 3', ' 4'], [' 5', ' 6', ' 7', ' 8'],[ ' 9', '10', '11', '12'], ['13', '14', '15', ' X']]

def find_pos(alist, item):
    for i in alist:
        for j in range(4):
            if i[j] == item:
                row = alist.index(i)
                col = j
                return row, col

row, col = find_pos(puzzle,' X')

print(row)

请注意，如果未找到该项目，它将返回None(因为默认情况下，不返回任何内容的每个函数都将返回None)，在这种情况下，代码将引发错误.

Note that if the item isn't found, it will return None (because every function that doesn't return anything returns None by default), in which case the code will throw an error.

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