Question

我正在学习处理Python 3.6中的函数。我尝试设置一个函数来计算特定单词在文本文件中出现的次数，但是我遇到了NameError问题。

我在pythontutor.com上尝试了该工具，以可视化代码步骤来找出原因。函数count_num中count_word的值似乎没有传递给for循环。但是我真的不明白为什么。

filenames = [
    "The Wallypug in London.txt", 
    "Chats on Old Silver.txt", 
    "Jack Jingle, and Sucky Shingle.txt", 
    "Superstition and Force.txt"
]


def count_word(filename, word):
    with open(filename) as open_file:
        file_content = open_file.read()

    count_num = file_content.lower().count(word)
    return count_num


for filename in filenames:
    count_word(filename, "great")
    print('There are ' + str(count_num) + " 'great' in " + filename + ".")

我希望输出为“ London.txt中的Wallypug中有89个'great'。但是它只是返回，

NameError: name 'count_num' is not defined

Answer 1

您在此行中缺少作业

    count_word(filename, "great")

更改为

    count_num = count_word(filename, "great")

Answer 2

这可能有帮助：

filenames = [
    "The Wallypug in London.txt", 
    "Chats on Old Silver.txt", 
    "Jack Jingle, and Sucky Shingle.txt", 
    "Superstition and Force.txt"
]

count_num ="" #define count_num here
def count_word(filename, word):
    count_num=0
    return count_num


for filename in filenames:
    count_word(filename, "great")
    print('There are ' + str(count_num) + " 'great' in " + filename + ".")

Answer 3

这是因为函数count_num中的count_word是局部变量，不能在全局区域中引用。将count_word(filename, "great")替换为count_num = count_word(filename, "great")

如何解决Python 3.6中的“ NameError”问题？

3 个答案: