str.index()与str.find()比较

最新推荐文章于 2025-04-06 12:08:26 发布

转载最新推荐文章于 2025-04-06 12:08:26 发布 · 673 阅读

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原文链接：http://www.cnblogs.com/lmgsanm/p/8331151.html

本文介绍了在Python中从带有特定标签的字符串中提取内容的两种方法：使用str.index()和str.find()。str.index()会在找不到子字符串时抛出异常，而str.find()则会返回-1。通过实例演示了如何定位并提取标签之间的内容。

 1 def extract_from_tag(tag,line):
 2     opener = "<" + tag + ">"
 3     closer = "</" + tag + ">"
 4     try:
 5         i = line.index(opener)# i = 7
 6         start = i + len(opener) # start = 7 + 5 =12
 7         j = line.index(closer,start) #j =16
 8         return line[start:j] # retrun line[12:16]
 9     except ValueError:
10         return None
11 a = extract_from_tag("red","what a <red>reosedf</red> this is")
12 print(a)
13 print(len(a))

str.index()

 1 def extract_from_tag(tag,line):
 2     opener = "<" + tag + ">"
 3     closer = "</" + tag + ">"
 4     i = line.find(opener) # i = 7
 5     if i != -1:
 6         start = i + len(opener) #start = 7+5=12
 7         j = line.find(closer,start) # j = 19
 8         if j !=-1:
 9             return line[start:j]  #line[12:19]
10     return None
11 a = extract_from_tag("red","what a <red>rose</red> this is")
12 print(a)