Python program to check for URL in a string

This article will teach you how to determine whether a string contains a URL or not. In Python, strings are collections of bytes that represent Unicode characters. When given a string, we will first determine whether it contains a URL and then extract it using regular expressions.

Using findall() Method

We will use Python's regular expression concept to solve this problem. Regular expressions are supported by the Python re module. The findall() method returns a list of all matches found in the string, scanning from left to right.

Syntax

re.findall(pattern, string)

Example

Here's a simple function to check and extract URLs from a string ?

import re

def checkURL(text):
    # Regular expression pattern to match URLs
    regex = r'http[s]?://(?:[a-zA-Z]|[0-9]|[$-_@.&+]|[!*\(\),]|(?:%[0-9a-fA-F][0-9a-fA-F]))+'
    urls = re.findall(regex, text)
    return urls

# Test string with URL
text = "Visit https://www.tutorialspoint.com/python for Python tutorials"
result = checkURL(text)
print("URLs found:", result)

URLs found: ['https://www.tutorialspoint.com/python']

Enhanced Example with Validation

This example checks if URLs exist and provides appropriate feedback ?

import re

def find_urls(text):
    regex = r'http[s]?://(?:[a-zA-Z]|[0-9]|[$-_@.&+]|[!*\(\),]|(?:%[0-9a-fA-F][0-9a-fA-F]))+'
    urls = re.findall(regex, text)
    
    if urls:
        return f"URLs found: {urls}"
    else:
        return "No URLs found in the string"

# Test with URL
text1 = "Check out https://www.python.org and https://www.tutorialspoint.com"
print(find_urls(text1))

# Test without URL
text2 = "This is just a plain text without any web links"
print(find_urls(text2))

URLs found: ['https://www.python.org', 'https://www.tutorialspoint.com']
No URLs found in the string

Using search() Method

The search() method finds the first occurrence of a pattern in the string. It returns a match object if found, or None if no match is found.

Syntax

re.search(pattern, string)

Example

Using search() to find and extract the first URL ?

import re

def find_first_url(text):
    regex = r'http[s]?://(?:[a-zA-Z]|[0-9]|[$-_@.&+]|[!*\(\),]|(?:%[0-9a-fA-F][0-9a-fA-F]))+'
    match = re.search(regex, text)
    
    if match:
        return match.group()
    else:
        return "No URL found"

# Test string
text = "Visit https://www.tutorialspoint.com and also check https://www.python.org"
first_url = find_first_url(text)
print("First URL found:", first_url)

First URL found: https://www.tutorialspoint.com

Comparison

Complete Example

Here's a comprehensive function that demonstrates both methods ?

import re

def analyze_urls(text):
    regex = r'http[s]?://(?:[a-zA-Z]|[0-9]|[$-_@.&+]|[!*\(\),]|(?:%[0-9a-fA-F][0-9a-fA-F]))+'
    
    # Find all URLs
    all_urls = re.findall(regex, text)
    
    # Find first URL
    first_match = re.search(regex, text)
    first_url = first_match.group() if first_match else None
    
    print(f"Text: {text}")
    print(f"All URLs: {all_urls}")
    print(f"First URL: {first_url}")
    print(f"Total URLs found: {len(all_urls)}")
    print("-" * 50)

# Test cases
test_texts = [
    "Visit https://www.tutorialspoint.com for tutorials",
    "Check https://www.python.org and https://docs.python.org/3/",
    "No URLs in this plain text"
]

for text in test_texts:
    analyze_urls(text)

Text: Visit https://www.tutorialspoint.com for tutorials
All URLs: ['https://www.tutorialspoint.com']
First URL: https://www.tutorialspoint.com
Total URLs found: 1
--------------------------------------------------
Text: Check https://www.python.org and https://docs.python.org/3/
All URLs: ['https://www.python.org', 'https://docs.python.org/3/']
First URL: https://www.python.org
Total URLs found: 2
--------------------------------------------------
Text: No URLs in this plain text
All URLs: []
First URL: None
Total URLs found: 0

Conclusion

Use re.findall() when you need to extract all URLs from a string, and re.search() when you only need the first URL. Both methods use regular expressions to match URL patterns effectively in text.