Python Slice Operator Syntax
To get a substring from a string using the slice method, you can use the following syntax:
- start: the starting index of the substring. The value at this index is included in the substring. If no start is specified, it should be 0.
- end: the ending index of the substring. The value at this index is not included in the substring. If no end is specified or the specified value exceeds the length of the string, it defaults to the length of the string.
- step: every step character after the current character must be included. If the step value is omitted, it is assumed to default to 1. When you pass a step value of -1 and omit the start and end values, the slice operator reverses the string.
Python Substring Templates
- string[start:end] - the syntax for getting all characters from the start of the index to the end of -1
- string[:end] - the syntax for getting all characters from the beginning of the line to the end of -1
- string[start:] - the syntax for getting all characters from the start of the index to the end of the string
- string[start:end:step] - the syntax to get all characters from start to end -1 at a discount per step character
How to extract a substring using a regular expression in Python?
Regular expressions are a powerful string manipulation tool in Python that is natively supported in Python. To extract a substring from a string using regular expressions, you must first import the "re" module into your code. The re.search() method takes a regular expression pattern as its first parameter and a string as its second parameter and returns the matching portion of the string as its result. In the Python substring example below, the re.search() method returns the substring in the group at index 1.