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Articles by Sarika Singh
Page 13 of 15
What is the Python regular expression to check if a string is alphanumeric?
In this article, we focus on how to check if a string is alphanumeric using regular expressions in Python. Regular expressions are very useful for pattern matching and validation. To use them, first import the re library, which is included by default in Python. The regular expression ^[a-zA-Z0-9]+$ matches strings that contain only letters (both uppercase and lowercase) and numbers. Let's break down this pattern − ^ − Matches the beginning of the string [a-zA-Z0-9] − Character class that matches any lowercase letter (a-z), uppercase letter (A-Z), or digit ...
Read MoreHow to catch StandardError Exception in Python?
In Python 2, StandardError was a built-in exception class that served as a base class for all built-in exceptions except for SystemExit, KeyboardInterrupt, and GeneratorExit. Using this class, we were able to catch the most common runtime errors in a single except block. However, since Python 3, the StandardError class has been deprecated, and now all built-in exceptions directly inherit from the Exception class. If you are using Python 3, you should catch exceptions using Exception instead of StandardError. StandardError in Python 2 The StandardError class in Python 2 was designed to catch all standard exceptions that ...
Read MoreDifference between attributes and properties in python?
In Python, everything is an object, and every object has attributes and methods. Attributes are data variables that describe the object (such as name, age, or height), while properties are a special kind of attribute that use getter, setter, and deleter methods to control access to the underlying data. Attributes in Python Attributes are variables that belong to an object. They are usually defined in the __init__ method and accessed using dot notation ? Example class Dog: def __init__(self, name, age): self.name = name ...
Read MoreSaving Python functions in a Sqlite table
In Python, you can store a function as a text string in a SQLite database using the sqlite3 module. You cannot run the function directly from the database, but you can retrieve the code later and execute it using Python's exec() or eval() functions. This is helpful when you want to store or update function logic, like in code editors, plugins, or apps that run user-created scripts. Using sqlite3 and exec() Function The sqlite3 module is used to create and work with SQLite databases in Python. The exec() function can run Python code that is stored as a string, including ...
Read MoreThe return Statement in Python
The return statement in Python is used to send a value back from a function to its caller and exit the function. Since everything in Python is an object, the return value can be any object such as numeric types (int, float), collections (list, tuple, dict), or even other functions. Key features of the return statement − It cannot be used outside a function. Any code written after a return statement within the same block is dead code and will never be executed. If no value is specified, None is returned implicitly. Syntax def some_function(parameters): ...
Read MoreWhat is an anonymous function in Python?
Anonymous Function in Python An anonymous function is a function which doesn't have a name. We can return a value from an anonymous function, call it at the time of creation or, assign it to a variable. Instead of using the def keyword, which is used for regular functions, anonymous functions are defined using the lambda keyword. Hence, they are commonly referred to as lambda functions. Syntax Following is the syntax to create anonymous functions using the lambda keyword - lambda [args] : expression Although a lambda function can have only one expression, it can have any number ...
Read MoreHow can we create recursive functions in Python?
Recursion is a process where a function calls itself repeatedly with new input values, slowly moving toward a condition where it stops. This stopping condition is called the base case. It prevents the function from running endlessly and allows it to return a final result. In Python, we can create recursive functions by simply defining a function that calls itself. Every recursive function has two main components − Recursive Case: This is when the function calls itself to solve a smaller part of the problem. It keeps the process going. Base Case: This is the stopping point. It tells ...
Read MoreHow to use *args and **kwargs in Python?
In Python, functions usually have a fixed number of arguments. However, there are situations where we may want to pass a variable number of arguments. In such cases, Python provides two special constructs: *args and **kwargs. *args allows a function to accept any number of positional arguments. **kwargs allows a function to accept any number of keyword arguments. We will discuss both of these concepts deeply in this article. What is "*args" in Python? In Python, *args allows a function to accept any number of positional arguments. These arguments are collected into a tuple inside the function, allowing ...
Read MoreWhat are the allowed characters in Python function names?
In Python, function names follow specific rules. A valid function name can only contain certain characters, and it must follow the naming conventions defined in the Python language syntax. Using the correct characters ensures that your code runs without syntax errors and stays readable. Allowed Characters in Function Names Python function names can consist of the following characters - Letters (A–Z, a–z) Digits (0–9) — but not at the beginning Underscores (_) — often used to separate words Function names must follow these rules - Must start with a letter or underscore Cannot start with a digit ...
Read MoreHow to return a json object from a Python function?
In Python, you need to use the built-in json module to work with JSON data. When you want to return data from a function in JSON format, you can use the json.dumps() function to convert a Python dictionary (or similar object) into a JSON string. This is helpful when making APIs, sending data in web responses, or saving organized data in files. Using json.dumps() Function The json.dumps function is used to convert a Python object (like a dictionary or list) into a JSON-formatted string. Syntax Following is its basic syntax - json.dumps(python_object) Where python_object is usually a dictionary or list ...
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