re.match() in Python

re.match method in Python is used to check if a given pattern matches the beginning of a string. It’s like searching for a word or pattern at the start of a sentence. For example, we can use re.match to check if a string starts with a certain word, number, or symbol. We can do pattern matching using re.match in different ways like checking if the string starts with certain characters or more complex patterns.

import re

# Checking if the string starts with "Hello"
s = "Hello, World!"
match = re.match("Hello", s)

if match:
    print("Pattern found!")
else:
    print("Pattern not found.")

Pattern found!

Syntax of re.match

re.match(pattern, string, flags=0)

Parameters

• pattern: This is the regular expression (regex) that you want to match. It can be any string that defines a pattern, like r"\d" for a digit, or r"[A-Za-z]" for any letter (uppercase or lowercase).
• string: This is the string you want to check for the pattern. re.match will try to match the pattern only at the beginning of the string.
• flags (optional): This is an optional parameter that allows you to modify how the matching should behave. For example, you can use re.IGNORECASE to make the matching case-insensitive. If not provided, the default value is 0.

Returns

• If re.match finds a match at the beginning of the string, it returns a match object.
• If no match is found, it returns None.

Using re.match with Regular Expressions

Regular expressions (regex) allow us to search for more complex patterns. For example, let’s check if a string starts with a number.

import re

# Checking if the string starts with a number
s = "123abc"

# \d means any digit
match = re.match(r"\d", s)  
if match:
    print("Starts with a number.")
else:
    print("Doesn't start with a number.")

Starts with a number.

Accessing Match Object

The result of re.match is a match object if a match is found, or None if no match is found. If a match occurs, we can get more information about it.

import re

s = "Python is great"
match = re.match(r"Python", s)

if match:
    print(f"Match found: {match.group()}")  # .group() returns the matched string
else:
    print("No match.")

Match found: Python