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ng6sk13pxjx
Asked:2025-04-04 07:35:15 +0000 UTC2025-04-04 07:35:15 +0000 UTC

通过字典中的 len 创建检查时无法输出两个答案选项

  • 772
favorite_languages = {
    'jen': ['python', 'ruby'],
    'sarah': 'c',
    'edward': ['ruby', 'go'],
    'phil': ['python', 'haskell'],
}
for name, languages in favorite_languages.items():
    if len(languages) >= 2 in favorite_languages:
        print(f"\n{name.title()}'s favorite  language's are:")
        for language in languages:
            print(language)
    else:
        print(f"\n{name.title()}'s favorite  language are:")
        for language in languages:
            print(language)

但这支队伍if被放行了。如果通过 查询字典值的长度print，它会打印2, 1, 2, 2。

python

1 个回答

  1. Best Answer

    问题是'sarah': 'c'，也就是说，'c'它是一个字符串，而不是一个列表。

    print(len("abc")) # 3
print(len("a")) # 1
print(len(["a", "b"])) # 2

    此外，您的代码if len(languages) >= 2 in favorite_languages会检查该项目是否存在于字典中，因此在这个例子中len(languages) >= 2它将是True或False，然后它将检查该True或是否False作为键存在favorite_languages（运算符in）。

    或者我们调整

    favorite_languages = {
    'jen': ['python', 'ruby'],
    'sarah': ['c'],
    'edward': ['ruby', 'go'],
    'phil': ['python', 'haskell'],
}

    或者

    favorite_languages = {
    'jen': ['python', 'ruby'],
    'sarah': 'c',
    'edward': ['ruby', 'go'],
    'phil': ['python', 'haskell'],
}

for name, languages in favorite_languages.items():
    is_list = isinstance(languages, list)
    count = len(languages) if is_list else 1
    message = "languages are" if count >= 2 else "language is"

    print(f"\n{name.title()}'s favorite {message}:")

    if is_list:
        for language in languages:
            print(f"- {language.title()}")
    else:
        print(f"- {languages.title()}")
    • 2

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