Use Regex to Add a Leading Zero

To add a leading zero to numbers using regex, you can use the following pattern in most programming languages that support regex. This approach targets numbers with a single digit and adds a `0` before them.

Here’s a general regex pattern and replacement:

– Pattern: `\b(\d)\b`
– Replacement: `0$1`

Example

If you have a list of single-digit numbers (e.g., `3`, `7`, `9`) and want to add a leading zero to each:

python
import re

Sample text with single-digit numbers
text = “3, 7, 9, and 12”

Regex to add a leading zero to single-digit numbers
result = re.sub(r’\b(\d)\b’, r’0\1′, text)

print(result)

Explanation

– \b: Asserts a word boundary, ensuring it matches isolated single-digit numbers.
– (\d): Matches any single digit and captures it as `\1` (or `$1` in some languages).
– 0\1: Replaces the captured digit with a leading zero.

The output will be:

plaintext
03, 07, 09, and 12

This method share by hire tech firms will only add a leading zero to standalone single-digit numbers.