##### Problem Statement
Write a function to validate an email address. The function should check if the given email address is in the correct format. The correct format for an email address is as follows:

- It must have the format `local@domain`.
- The `local` part can contain alphanumeric characters and special characters `._%+-`.
- The `domain` part can contain alphanumeric characters and hyphens `-`.
- The `domain` part must contain at least one dot `.` with at least one character before and after it.
- The overall length of the email should be no more than 254 characters.

##### Example
```plaintext
Input: email = "test.email+alex@leetcode.com"
Output: True

Input: email = "test.email.leetcode.com"
Output: False
```

##### Constraints
- The email address string will be a non-empty string.

#### Expected Challenge Output
When the function `isValidEmail` is called with the given example input, the expected output is a boolean indicating whether the email is valid or not.

##### Problem Statement
Write a function to validate an email address. The function should check if the given email address is in the correct format. The correct format for an email address is as follows:

- It must have the format `local@domain`.
- The `local` part can contain alphanumeric characters and special characters `._%+-`.
- The `domain` part can contain alphanumeric characters and hyphens `-`.
- The `domain` part must contain at least one dot `.` with at least one character before and after it.
- The overall length of the email should be no more than 254 characters.

##### Example
```plaintext
Input: email = "test.email+alex@leetcode.com"
Output: true

Input: email = "test.email.leetcode.com"
Output: false
```

##### Constraints
- The email address string will be a non-empty string.

#### Expected Challenge Output
When the function `isValidEmail` is called with the given example input, the expected output is a boolean indicating whether the email is valid or not.

JavaScript

JavaScript is a high-level, dynamic, and interpreted programming language that is widely used for web development and beyond. It was created in the mid-1990s and has since become one of the most popular and widely used programming languages in the world. JavaScript allows developers to create interactive and dynamic websites, as well as build complex web applications and server-side programs. It is a versatile language that can run on any modern web browser, as well as server environments like Node.js, making it an essential tool for any full-stack web developer.

learn-javascript

Python

Python is a high-level, interpreted, general-purpose programming language. It was created in the late 1980s by Guido van Rossum and has since become one of the most popular programming languages in the world. Python is known for its simple and easy-to-read syntax, making it a great language for beginners to learn, and for experienced developers to write complex applications.

Python is used in a variety of applications, including web development, scientific computing, data analysis, artificial intelligence, and more. It has a large and active community of users and developers who have created many libraries and frameworks that make it easier to build complex applications quickly. Python is also known for its strong support for object-oriented programming and its dynamic typing, which makes it flexible and easy to use.

Overall, Python is a versatile and powerful language that can be used for a wide range of applications, making it a great choice for developers looking to build anything from simple scripts to complex applications.

learn-python

C++ Programming

C++ is a high-level, general-purpose programming language that was created as an extension of the C programming language. It is widely used for developing systems software, game development, and desktop and mobile applications. C++ is known for its performance, efficiency, and versatility, making it a popular choice for developing resource-intensive applications. It is also used in the development of other programming languages, as well as in various scientific and engineering applications. C++ is considered a mid-level language, as it contains both high-level and low-level programming concepts, and provides control over system resources through its use of pointers and manual memory management.

learn-cpp-programming

C Programming

This C fundamentals learning module is designed to teach individuals the basics of programming using the C programming language. The module typically covers the fundamentals of C programming, including topics such as data types, variables, control structures, functions, pointers, and memory management. The module may also cover more advanced topics, such as file handling, dynamic memory allocation, and multithreading.

learn-c-programming

Email Address Validator

email-address-validator

Regular Expression

Regular expressions, also known as regex or regexp, serve as a powerful tool for manipulating text and data. They are a sequence of characters that form a search pattern, often used with string methods or in applications that require data extraction. In this chapter, we'll illuminate important concepts around regular expressions and their implementation in Python.

Python's built-in function `re` supports regular expressions operations like matching, searching, splitting, and replacing the strings. To use regular expressions in Python, you should import the `re` module using the import statement.

```python
import re
```
Let's start by understanding the basic regular expression syntax through various examples. Some of the commonly used metacharacters, which hold special meanings in regular expressions, include `. ^ $ * + ? { } [ ] \ | ( )`. In the context of regex, these characters can't be used literally.

An important operation in regex is pattern matching. Let's use `re.match()` function for this:

```python
import re
  
# Match the pattern at the start of the text
print(re.match('python', 'python is easy to learn'))

# Output: <re.Match object; span=(0, 6), match='python'>
```

Here, `re.match()` function returns a match object if the pattern is located at the beginning of the string. If matching fails, it returns None.

Now, let's discuss `re.search()`. `re.search(pat, str)` function searches the pattern pat in the string str and returns a match object if found, else it returns None.

```python
import re
  
# Search the pattern in the text
print(re.search('easy', 'python is easy to learn'))

# Output: <re.Match object; span=(9, 13), match='easy'>
```

`re.findall()` returns all non-overlapping matches of pattern in string, as a list of strings. Here’s an example:

```python
import re
  
# Find all occurrence of the pattern
print(re.findall('a', 'abcdaef'))

# Output: ['a', 'a']
```

In the example above, `re.findall()` returns a list containing all occurrences of 'a'.

Regular expressions also leverage metacharacters for more complex pattern searching. Square brackets `[ ]` in regular expressions are used to include a set of characters, any one of which can match.

```python
import re
  
# find words starting with 'a' and ending with 'd'
print(re.findall('[a-z]*d', 'abcd abc abd add'))

# Output: ['abcd', 'abd', 'add']
```
In this example, the pattern `[a-z]*d` matches words starting with any lowercase letter and ending with 'd'.

In summary, Python's `re` module, which provides full support for Perl-like regular expressions, is a potent weapon in any Python programmer's armory. It is crucial to understand and utilize it well in order to manipulate strings effectively and efficiently.

We’ve covered the basics of regular expression in Python, including various functions such as `re.match()`, `re.search()`, and `re.findall()`. As you practice these and dive deeper into Python, remember to experiment with different patterns and functions. Keep practicing for solid mastery over regular expressions.

Email Address Validator

Challenge Instructions

Problem Statement

Example

Constraints

Expected Challenge Output

Test Cases