Input Validation in Python Last Updated : 18 Apr, 2025 Comments Improve Suggest changes Like Article Like Report Input validation ensures that data entered by the user is correct, safe, and in the expected format. In Python, input validation is essential for creating robust, error free programs that can handle incorrect or unexpected inputs. Python provides several ways to validate user inputs, let's explore some.Using try-except for Type ValidationOne of the simplest methods to ensure the input is of the correct type is to use a try-except block. For example, when accepting numeric input, we can ensure that the user enters a valid integer. Python while True: try: num = int(input("Enter a number: ")) break except ValueError: print("Invalid input!") print(num) OutputEnter a number: 5 5Explanation: If the user enters something that cannot be converted to an integer (like a string), a ValueError is raised, and the user is prompted again.Using if Statements for Range ValidationFor situations where you need to ensure the input is within a certain range, you can use a simple if statement. Python while True: age = int(input("Enter age: ")) if 0 <= age <= 120: break else: print("Enter a valid age inside the range (0-120)") print(age) OutputEnter age: 144 Enter a valid age inside the range (0-120) Enter age: 23 23Explanation: In this case, the function will repeatedly prompt the user until they enter a valid age.Using Regular Expressions for Format ValidationFor more complex input validation, such as ensuring an email address or phone number follows a particular format, regular expressions (regex) are useful. Python import re while True: email = input("Enter email: ") pattern = r"^[a-zA-Z0-9_.+-]+@[a-zA-Z0-9-]+\.[a-zA-Z0-9-.]+$" if re.match(pattern, email): break else: print("Invalid email format") print(email) OutputEnter email: aryan.tanwar Invalid email format Enter email: [email protected] [email protected]Explanation: regular expression pattern ensures that the input matches the typical structure of an email address.Related Articles:Python Try ExceptPython RegExPython StringPython Tutorial Comment More infoAdvertise with us Next Article Input Validation in Python A anuragtriarna Follow Improve Article Tags : Python Python Programs python-input-output Practice Tags : python Similar Reads Input Validation in Python String In Python, string input validation helps ensure that the data provided by the user or an external source is clean, secure and matches the required format. In this article, we'll explore how to perform input validation in Python and best practices for ensuring that strings are correctly validated.Pyt 2 min read Python String Input Output In Python, input and output operations are fundamental for interacting with users and displaying results. The input() function is used to gather input from the user and the print() function is used to display output.Input operations in PythonPythonâs input() function allows us to get data from the u 3 min read Get User Input in Loop using Python In Python, for and while loops are used to iterate over a sequence of elements or to execute a block of code repeatedly. When it comes to user input, these loops can be used to prompt the user for input and process the input based on certain conditions. In this article, we will explore how to use fo 3 min read List As Input in Python in Single Line Python provides several ways to take a list as input in Python in a single line. 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Pythona = "Geeks\nfor\nGeeks" print(a)OutputGeeks f 2 min read Literals in Python Literals in Python are fixed values written directly in the code that represent constant data. They provide a way to store numbers, text, or other essential information that does not change during program execution. Python supports different types of literals, such as numeric literals, string litera 4 min read How to Initialize a String in Python In Python, initializing a string variable is straightforward and can be done in several ways. Strings in Python are immutable sequences of characters enclosed in either single quotes, double quotes or triple quotes. Letâs explore how to efficiently initialize string variables.Using Single or Double 2 min read How to Input a List in Python using For Loop Using a for loop to take list input is a simple and common method. It allows users to enter multiple values one by one, storing them in a list. This approach is flexible and works well when the number of inputs is known in advance.Letâs start with a basic way to input a list using a for loop in Pyth 2 min read How to Take List of Tuples as Input in Python? Lists of tuples are useful data structures in Python and commonly used when you need to group related elements together while maintaining immutability within each group. We may need to take input for a list of tuples from the user. This article will explore different methods to take a list of tuples 3 min read Like