String processing is a very common task in Python programming. The find() function is a very useful tool when we need to find the location of a substring in a string. This article will lead you to learn the usage of the find() function in depth, so that you can be more handy in Python string processing.
The find() function is a method for string (str) objects in Python, and its basic syntax is as follows:
str is the original string, sub is the substring to be found, and start and end are optional parameters that indicate the start and end positions of the lookup, respectively.
The find() function returns the index position where the substring first appeared in the original string. If the substring is not found, -1 is returned. It is important to note that the index of strings in python starts from 0.
1.Simple substring lookup
Use the find() function to find the location of a substring in a string. For example:
2.Combine the start and end locations for the lookup
By specifying the start and end parameters, it is possible to find substrings within a specific range of strings. For example:
3.Determine whether a substring exists
By checking the return value of the find() function, you can determine whether the substring exists in the original string. For example:
1.The find() function is case-sensitive, and if you need to ignore case for search, you can convert both the original string and substrings to lowercase (or uppercase) first, and then perform the search.
2.When the range specified by the start and end parameters exceeds the length of the original string, the find() function does not report an error, but automatically adjusts the range to the valid range of the string.
3.If you need to find a substring that contains special characters, you can use an escape symbol to handle it. For example, finding line breaks can be used""。
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