find方法返回的是子串出现的首位置。比如下面的这个,返回的是abc在str中的首位置也就是3。如果没找到将会返回-1 str = "dkjabcfkdfjkd198983abcdeefg" print str.find('abc') 1. 2. 但是在str中有2个abc,那么如何去查找到第二个abc的位置呢。由于find是会返回查找到的字符串的首位置,因此我们可以利用这个...
def extract_substring(string, start, end): # 使用切片操作提取子字符串 substring = string[start:end] return substring def extract_substring_with_find(string, substring): # 使用find()方法查找子字符串的位置 start = string.find(substring) if start == -1: return None end = start + len(substr...
To achieve our goal, we’ll use theindexmethod which is a function associated with a specific class and serves for a certain function when attached to a variable following a dot. Theindexmethod in particular, returns the index of the given substring, inside the string.The substring that we ...
find('o')) # 4 print(s.rfind('o')) # 7 print(s.rindex('o')) # 7 print(s.rindex('o', 8)) # ValueError: substring not found 性质判断 可以通过字符串的startswith、endswith来判断字符串是否以某个字符串开头和结尾;还可以用is开头的方法判断字符串的特征,这些方法都返回布尔值,代码如下...
find("n", 5, 13)) print(str.index("abc")) print(str.index("n", 5, 13)) 执行以上代码,输出结果为: Traceback (most recent call last): File ".py", line 6, in <module> print(str.index("n", 5, 13)) ^^^ ValueError: substring not found 0 11 -1 0 (2)检索字符串包含目标字...
ValueError: substring not found >>> str.index('n') #同find类似,返回第一次匹配的索引值 4 >>> str.rindex('n') #返回最后一次匹配的索引值 11 >>> >>> str.count('a') #字符串中匹配的次数 0 >>> str.count('n') #同上 2
在您的 Python 生涯中,有一些基本的字符串操作您可能会用到很多次,比如len(字符串的长度)、连接、迭代、索引和切片(Python 的 substring 操作的等价物)。举例来说,在空闲会话中键入以下代码,注意结果与您在这里看到的输出相匹配:>>> len('shrubbery') 9 'shrubbery' is 9 characters long. >>> 'spam' +...
str.find() 查找 代码语言:javascript 代码运行次数:0 运行 AI代码解释 In [90]: help(s1.find) Help on built-in function find: find(...) S.find(sub [,start [,end]]) -> int Return the lowest index in S where substring sub is found, such that sub is contained within S[start:end]...
def count(s, sub): result = 0 for i in range(len(s) + 1 - len(sub)): result += (s[i:i + len(sub)] == sub) return result The behavior is due to the matching of empty substring('') with slices of length 0 in the original string.Contributing...
def index(self, sub, start=None, end=None): # real signature unknown; restored from __doc__ (和find差不多) """ S.index(sub[, start[, end]]) -> int Return the lowest index in S where substring sub is found, (返回找到提交字符串子字符串的最低索引,这样的子被包含在S[start.end]...