php - Regular expression for only allowing alphanumeric, dashes, underscores

Hey folks,

I stumbled upon a similar issue in PHP where I needed to allow only alphanumeric characters, dashes, and underscores in a particular string. After some trial and error, I found a regex pattern that did the job for me.

Here's the regex pattern that you could use:

php
/^[a-zA-Z0-9\-\_]+$/

php
$username = $_POST['username']; // Assuming you're retrieving the input from a form



if (preg_match('/^[a-zA-Z0-9\-\_]+$/', $username)) {

    // Proceed with the desired logic for a valid username

} else {

    // Handle the case of an invalid username

}

Hey there!

I ran into a similar issue a while back while working on a PHP project. To restrict a field to alphanumeric characters, dashes, and underscores only, you can use the following regular expression pattern:

/^[a-zA-Z0-9-_]+$/

php
$username = $_POST['username']; // assuming the input is coming from a form



if (preg_match('/^[a-zA-Z0-9-_]+$/', $username)) {

    // Valid username

    // Proceed with further logic

} else {

    // Invalid username

    // Display an error message

}

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Hey everyone,

I had a similar requirement while working on a PHP project. I needed to restrict user input to only allow alphanumeric characters, underscores, and dashes in a specific field. After some experimentation, I managed to solve it using a regular expression pattern.

Here's the regex pattern that worked for me:

php
/^[a-zA-Z0-9_-]+$/

php
$username = $_POST['username']; // Assuming the user input comes from a form field



if (preg_match('/^[a-zA-Z0-9_-]+$/', $username)) {

    // Valid username

    // Proceed with further logic

} else {

    // Invalid username

    // Display an error message

}

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