When working with PHP, you may need to convert a Unicode string to uppercase. This guide explains the operation, shows what its arguments mean, and uses three separate examples to make the result easier to understand.
mb_strtoupper: This applies Unicode uppercase mappings and can expand some characters into multiple code points.
What Is mb_strtoupper in PHP?
Convert a Unicode string to uppercase. This applies Unicode uppercase mappings and can expand some characters into multiple code points.
Syntax:
mb_strtoupper(string $string, ?string $encoding = null): string
Parameters and return value: The signature above identifies the arguments and return type where the API has a single call. For topic guides, follow the sequence of calls in the examples. Always distinguish a returned value from an object or variable modified by reference.
Important: The result may have a different character count. Avoid using uppercase transformation as an immutable identifier.
Example 1: Basic Usage
This example introduces the operation with a short and predictable input.
<?php
echo mb_strtoupper("café", "UTF-8");
The code focuses on the main operation. This applies Unicode uppercase mappings and can expand some characters into multiple code points.
Example 2: Another Case
Now compare a different input, locale, date, or option to see another part of the behavior.
<?php
echo mb_strtoupper("hello", "UTF-8");
What changes? The result may have a different character count. Avoid using uppercase transformation as an immutable identifier.
Practical Example: Applying It in an Application
Use the following separate example as a starting point for a small application task. Check any extension or environment requirements below before running it.
<?php
$labels = ["urgent", "résumé", "complete"];
foreach ($labels as $label) {
echo mb_strtoupper($label, "UTF-8") . PHP_EOL;
}
The practical example demonstrates how to apply this operation to multiple values, a reusable task, or a validated input. This applies Unicode uppercase mappings and can expand some characters into multiple code points.
Important Behavior and Edge Cases
- Core behavior: This applies Unicode uppercase mappings and can expand some characters into multiple code points.
- Inputs and results: The result may have a different character count. Avoid using uppercase transformation as an immutable identifier.
- Alternatives: mb_strtolower() converts to lowercase and mb_convert_case() supports title case.
- Compatibility: mbstring is required for mb_* functions.
Comparison With Related Functions
| Function or Approach | When to Use It |
|---|---|
mb_strtoupper | Convert a unicode string to uppercase. |
| Related PHP approach | mb_strtolower() converts to lowercase and mb_convert_case() supports title case. |
Common Beginner Mistakes
| Mistake | Correct Approach |
|---|---|
| Using an incorrect input or option | The result may have a different character count. Avoid using uppercase transformation as an immutable identifier. |
| Confusing this API with a related operation | mb_strtolower() converts to lowercase and mb_convert_case() supports title case. |
| Assuming output is identical across environments | Check return values and required extensions or versions. mbstring is required for mb_* functions. |
Key Takeaways
- mb_strtoupper helps you convert a Unicode string to uppercase.
- This applies Unicode uppercase mappings and can expand some characters into multiple code points.
- The result may have a different character count. Avoid using uppercase transformation as an immutable identifier.
Use mb_strtoupper when you need to convert a Unicode string to uppercase. Start with the first example, compare the second, and adapt the practical example to your inputs. Confirm the return value and environment requirements before adding it to production code.