List of articles

• Python index() Method ： Detects whether a string contains a substring

Python index() Method ： Detects whether a string contains a substring

Same as find() The method is similar to ,index() Method can also be used to retrieve whether the specified string is included , The difference is , When the specified string does not exist ,index() The method throws an exception .

index() The syntax of the method is as follows ：

str.index(sub[,start[,end]])

The meanings of parameters in this format are ：

• str： Represents the original string ;
• sub： Represents the substring to retrieve ;
• start： Indicates the starting position of the search , If you don't specify , Search from scratch by default ;
• end： Indicates the end of the search , If you don't specify , The default is to retrieve all the way to the end .

【 example 1】 use index() Method retrieval “c.biancheng.net” First time in “.” Location index of .

>>> str = "c.biancheng.net"
>>> str.index('.')
1

【 example 2】 When retrieval fails ,index() It throws an exception .

>>> str = "c.biancheng.net"
>>> str.index('z')
Traceback (most recent call last):
File "<pyshell#49>", line 1, in <module>
str.index('z')
ValueError: substring not found

Same as find() and rfind() equally , String variables also have rindex() Method , Its function and index() The method is similar to , The difference is that it searches from the right , for example ：

>>> str = "c.biancheng.net"
>>> str.rindex('.')
11