When working with PHP, you may need to check whether a multibyte regular expression matches at the beginning. This guide explains the operation, shows what its arguments mean, and uses three separate examples to make the result easier to understand.
mb_ereg_match: The match is anchored at the beginning of the input. This differs from searching anywhere in the text.
What Is mb_ereg_match in PHP?
Check whether a multibyte regular expression matches at the beginning. The match is anchored at the beginning of the input. This differs from searching anywhere in the text.
Syntax:
mb_ereg_match(string $pattern, string $string, ?string $options = null): bool
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: mb_ereg uses Oniguruma patterns, not PCRE slash-delimited patterns used by preg_match().
Example 1: Basic Usage
This example introduces the operation with a short and predictable input.
<?php
var_dump(mb_ereg_match("^[A-Z]+", "ABC123"));
The code focuses on the main operation. The match is anchored at the beginning of the input. This differs from searching anywhere in the text.
Example 2: Another Case
Now compare a different input, locale, date, or option to see another part of the behavior.
<?php
var_dump(mb_ereg_match("^[0-9]+", "room42"));
What changes? mb_ereg uses Oniguruma patterns, not PCRE slash-delimited patterns used by preg_match().
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
$codes = ["ABC-123", "123-ABC", "XYZ-900"];
foreach ($codes as $code) {
if (mb_ereg_match("^[A-Z]{3}-[0-9]{3}$", $code)) {
echo $code . PHP_EOL;
}
}
The practical example demonstrates how to apply this operation to multiple values, a reusable task, or a validated input. The match is anchored at the beginning of the input. This differs from searching anywhere in the text.
Important Behavior and Edge Cases
- Core behavior: The match is anchored at the beginning of the input. This differs from searching anywhere in the text.
- Inputs and results: mb_ereg uses Oniguruma patterns, not PCRE slash-delimited patterns used by preg_match().
- Alternatives: Use mb_ereg() to search anywhere in a string and preg_match() when PCRE is required.
- Compatibility: mbstring is required for mb_* functions.
Comparison With Related Functions
| Function or Approach | When to Use It |
|---|---|
mb_ereg_match | Check whether a multibyte regular expression matches at the beginning. |
| Related PHP approach | Use mb_ereg() to search anywhere in a string and preg_match() when PCRE is required. |
Common Beginner Mistakes
| Mistake | Correct Approach |
|---|---|
| Using an incorrect input or option | mb_ereg uses Oniguruma patterns, not PCRE slash-delimited patterns used by preg_match(). |
| Confusing this API with a related operation | Use mb_ereg() to search anywhere in a string and preg_match() when PCRE is required. |
| Assuming output is identical across environments | Check return values and required extensions or versions. mbstring is required for mb_* functions. |
Key Takeaways
- mb_ereg_match helps you check whether a multibyte regular expression matches at the beginning.
- The match is anchored at the beginning of the input. This differs from searching anywhere in the text.
- mb_ereg uses Oniguruma patterns, not PCRE slash-delimited patterns used by preg_match().
Use mb_ereg_match when you need to check whether a multibyte regular expression matches at the beginning. 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.