The easiest way is via Python’s in operator. Following are the allowed Alphanumeric Characters. I need to check a string containing only a..z, 0..9, and . Python program to check if a string contains all unique characters. This function returns the first index position where substring is found, else returns -1. An area of application would be, for example, to check user names which may contain only certain characters. I am not clear now how to do it with a regular expression. Python | Ways to check if given string contains only letter. Using a for loop check the entire string and extract only character elements using the isalpha() function. RegEx can be used to check if a string contains the specified search pattern. In Python, there’s a similar method called index(): Check if string contains special characters in Swift; How to check if a string contains only whitespace letters in Python? You can try both methods in our interactive Python shell (just click "Run" to execute the code in … The Most Pythonic Way to Check if a Python String Contains Another String? I was hoping I could use something like regex for this but am struggling. str.isdigit() returns True if all the characters in the given string are digits, False otherwise. Sample Solution:- Python … If you are coming to Python from Java, for instance, you might have used the contains method to check if some substring exists in another string. In this article, we'll examine four ways to use Python to check whether a string contains a substring. Compare Strings in Bash. Python string is a sequence of characters and each character in it has an index number associated with it. #python; #string; #substring; How to check if a character / substring is in a string or not # Let me start with a little history about myself. Python | Check whether string contains only numbers or not. Python Strings Slicing Strings Modify Strings Concatenate Strings Format Strings Escape Characters String Methods String Exercises. Python