我制作了一个程序，允许用户输入一个字母，然后显示以该字母开头的单词。我从这个页面得到了我的程序的实际字母：
How to find a word that starts with a specific character
具体来说：re.findall（r＆＃39; \ bs \ w +＆＃39;，text）
为了让用户能够输入任何字母，我创建了一个输入（字母）和一部分代码，将该输入转换为大写和小写变量，称为letterupper和letterlower。然后我改变了代码：
words = re.findall(r'\bs\w+', text)
为：
words = re.findall(r'\b[(lowerletter)(upperletter)]\w+', text)
问题是当我现在运行我的程序时，它会根据您输入的输入提供随机单词。例如，我输入了字母K，它给了我以r，u，p，t等开头的单词... lowerletter和upperletter变量确实存储了正确的信息，因为当我打印它们时它们包含大小写版本我输入的那封信。我不知道发生了什么。
完整代码减去以下几百字：
import re
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letter = input ("Please Enter the Letter you want to find the words beggining with.")
upperletter = letter.upper()
lowerletter = letter.lower()
words = re.findall(r'\b[(lowerletter)(upperletter)]\w+', text)
print (words)
答案 0 :(得分：2)
使用+运算符将变量与原始正则表达式连接起来。
words = re.findall(r'\b[' + lowerletter + upperletter +r']\w+', text)
答案 1 :(得分：0)
用split（）分解文本，我们比较每个单词的第一个字母降低到输入，在着名列表理解中：
letter = raw_input ("Please Enter the Letter you want to find the words beggining with: ")
words = [word for word in text.split() if word.lower()[0] == letter.lower())
print (words)
一些有趣的观点：使用raw_input，因为它不被解释;如果您将word.lower()[0]替换为word.lower().startswith( letter.lower() )，则可以检查多个字符。最后，如果我们使用生成器，它的内存效率更高（而且更有趣:);最后两行是：
words = (word for word in text.split() if word.lower()[0] == letter.lower())
for word in words:
print word