How to Change the Case of Generated License Keys in PHP: Uppercase vs Lowercase

Pass 'upper' or 'lower' as the third argument to the SunLicense constructor to control whether generated license keys contain uppercase or lowercase letters.

When generating license keys with the msbatal/php-license-key-generator library, you can change the case of generated license keys to produce either uppercase or lowercase output. The SunLicense class provides a dedicated $case property that controls this behavior during instantiation or at runtime.

How the Case Parameter Works in SunLicense.php

The SunLicense class in SunLicense.php exposes a $case property that determines the character set used during key generation. According to the source code, this property defaults to 'upper' and accepts either 'upper' or 'lower' as valid values.

Constructor Signature and Default Behavior

When instantiating the SunLicense class, the third parameter controls letter casing:

public function __construct($prefix = null, $template = null, $case = 'upper', $count = null)

Lines 66-67 of SunLicense.php show the assignment logic:

if (!empty($case)) {
    $this->case = $case;               // case of letters (upper/lower)
}

The internal $case property defaults to 'upper' as declared on line 37.

Key Generation Logic

Inside the generate() method (line 120), the class uses conditional ASCII character generation based on the $case value:

if ($this->case == 'lower') {
    $key .= chr(rand(97, 122)); // generate lowercase letters   [lines 86-87]
} else {
    $key .= chr(rand(65, 90)); // generate uppercase letters   [lines 88-89]
}

This logic uses chr(rand(97, 122)) for lowercase a-z and chr(rand(65, 90)) for uppercase A-Z.

Setting License Key Case During Instantiation

Generate Uppercase Keys (Default)

To create license keys with uppercase letters, pass 'upper' as the third argument or omit it entirely to use the default:

<?php
require_once 'SunLicense.php';

$license = new SunLicense('SLK', 'AA99-9A9A-A9A9-99AA', 'upper', 3);
print_r($license->generate());
// Example output: ['SLK-AB12-CD34-EF56', 'SLK-GH78-IJ90-KL12', 'SLK-MN34-OP56-QR78']
?>

Generate Lowercase Keys

For lowercase output, explicitly pass 'lower' as implemented in msbatal/php-license-key-generator:

<?php
require_once 'SunLicense.php';

$license = new SunLicense('SLK', 'aa99-9a9a-a9a9-99aa', 'lower', 2);
print_r($license->generate());
// Example output: ['SLK-ab12-cd34-ef56', 'SLK-gh78-ij90-kl12']
?>

Changing Case After Object Creation

You can also change the case behavior by directly modifying the public $case property after instantiation. This approach is useful when you need to generate multiple batches with different casing using the same template configuration:

<?php
require_once 'SunLicense.php';

$license = new SunLicense('SLK', null, null, 1);   // defaults to upper
$license->case = 'lower';                         // manually override
echo $license->generate()[0];                     // e.g., SLK-ab12-cd34-ef56
?>

The test/SunLicense.php file in the repository contains additional usage examples demonstrating case configuration and validation.

Summary

• Constructor parameter: Pass 'upper' or 'lower' as the third argument to SunLicense to set the case of generated license keys.
• Default behavior: The library defaults to 'upper' case as defined in SunLicense.php at line 37.
• ASCII generation: Uppercase uses chr(rand(65, 90)) (lines 88-89); lowercase uses chr(rand(97, 122)) (lines 86-87).
• Runtime modification: The $case property remains publicly accessible, allowing case changes after object instantiation without creating a new instance.

Frequently Asked Questions

What is the default case for generated license keys?

The SunLicense class defaults to 'upper' case. This is defined in the property declaration on line 37 of SunLicense.php. If you omit the third constructor parameter or pass null, the generator will produce license keys containing uppercase letters A-Z.

Can I change the case after creating the SunLicense object?

Yes. The $case property is public, so you can modify it directly after instantiation. Set $license->case = 'lower' or $license->case = 'upper' before calling the generate() method to switch the output format without creating a new object.

Does the case setting affect the prefix or template characters?

No. The $case setting only affects randomly generated letter characters within the key segments. Literal characters defined in your prefix or template parameters remain exactly as specified. For example, if your template contains literal 'A' characters, they stay as 'A' regardless of the case setting.

What happens if I pass an invalid case value?

Any value other than 'lower' will result in uppercase letter generation. The generate() method checks if ($this->case == 'lower') (line 86); if this condition fails, the else clause (lines 88-89) executes, producing uppercase characters. Therefore, passing 'upper', 'mixed', or other strings defaults to uppercase behavior.

{
  "mcpServers": {
    "instagit": {
      "command": "npx",
      "args": ["-y", "instagit@latest"]
    }
  }
}