Python 检查一个值是否等于数组中的任何值
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Checking if a value is equal to any value in an array
提问by ThaRemo
I'm new to python (and programming in general) and I can't seem to find a solution to this by myself. I want to check the first letter of a string is equal to any letter stored in an array, something like this:
我是 python 的新手（以及一般的编程），我自己似乎无法找到解决方案。我想检查字符串的第一个字母是否等于存储在数组中的任何字母，如下所示：
letter = ["a", "b", "c"]
word = raw_input('Enter a word:')
first = word[0]
if first == letter:
print "Yep"
else:
print "Nope"
But this doesn't work, does anyone know how it will? Thanks in advance!
但这不起作用，有谁知道它会如何？提前致谢！
采纳答案by Sukrit Kalra
You need to use the inoperator. Use if first in letter:.
您需要使用in运算符。使用if first in letter:.
>>> letter = ["a", "b", "c"]
>>> word = raw_input('Enter a word:')
Enter a word:ant
>>> first = word[0]
>>> first in letter
True
And one False test,
还有一个错误的测试，
>>> word = raw_input('Enter a word:')
Enter a word:python
>>> first = word[0]
>>> first in letter
False
回答by Sukrit Kalra
Try using the inkeyword:
尝试使用in关键字：
if first in letter:
On your current code, you are comparing a string character (firstwhich equals the first character in word) to a list. So, let's say my input is "a word". What your code is actually doing is:
在您当前的代码中，您将一个字符串字符（first等于 中的第一个字符word）与一个列表进行比较。所以，假设我的输入是"a word". 你的代码实际上在做什么：
if "a" == ["a", "b", "c"]:
which will always be false.
这将永远是错误的。
Using the inkeyword however is doing:
in然而，使用关键字正在做：
if "a" in ["a", "b", "c"]:
which tests whether "a"is a member of ["a", "b", "c"]and returns true in this case.
在这种情况下，它测试是否"a"是 的成员["a", "b", "c"]并返回 true。
回答by squiguy
回答by Brian H
The problem as I see it, is that you are asking does a character equal an array. This will always return false.
在我看来，问题在于您问的是一个字符是否等于一个数组。这将始终返回 false。
Try using a loop to check 'first' against each item in 'letter'. Let me know if you need help on figuring out how to do this.
尝试使用循环检查“信件”中的每个项目的“第一项”。如果您需要帮助了解如何执行此操作，请告诉我。
