Скачать или смотреть Extracting the first number after a number and a period using Regex

Learn how to correctly use Regex to extract the first number after a numeral and a period from strings. This guide provides practical examples and code snippets for easy implementation.
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This video is based on the question https://stackoverflow.com/q/64991959/ asked by the user 'Mickey Gray' ( https://stackoverflow.com/u/13030248/ ) and on the answer https://stackoverflow.com/a/64992222/ provided by the user 'Barmar' ( https://stackoverflow.com/u/1491895/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Extracting the First Number After a Number and a Period with Regex

When working with text that includes ordered lists or numbered data, it's common to run into scenarios where you need to extract specific information from the string. For instance, in an ordered list containing names and addresses, you may want to extract the first number that follows a number and a period. This post will guide you through creating a Regex pattern that does just that.

The Problem

Consider the following list:

[[See Video to Reveal this Text or Code Snippet]]

In this structured order, you might want to retrieve the numbers 123 and 234 associated with each entry. A common mistake is to create a Regex pattern that returns all numbers rather than just those that suit the criteria. Let’s explore how to achieve the desired outcome.

The Correct Regex Solution

To solve this problem, we can use positive lookbehind assertions in our Regex pattern. This allows us to specifically check for the presence of the preceding number and period combination.

Regex Breakdown

The Regex we will use is as follows:

[[See Video to Reveal this Text or Code Snippet]]

Explanation of the Pattern

(?<=...): This is the lookbehind assertion that ensures a certain pattern precedes our target match.

^\d+ : This asserts that we are looking at the start of a new line and immediately checks for one or more digits (the leading number).

.: This matches the literal period that follows the leading number.

\D*: This matches any non-digit characters (including spaces or letters) that may come after the period.

\d+ : Finally, this matches one or more digits, which is the number we want to extract.

gm: These flags stand for global (find all matches) and multiline (allow ^ to match at the start of each line).

Implementation Example

Here’s an example of how to implement this in a JavaScript environment:

[[See Video to Reveal this Text or Code Snippet]]

Conclusion

By following the approach outlined above, you can successfully extract the first number after a numeral and period in any structured list. The power of Regex allows for flexible and efficient text parsing, making it an invaluable tool for programmers who regularly handle formatted data.

Feel free to try out the provided Regex and JavaScript code snippet in your programming environment, and expand on it based on your specific requirements. Happy coding!