When working with PHP, you may need to replace text matching a multibyte regular expression. This guide explains the operation, shows what its arguments mean, and uses three separate examples to make the result easier to understand.
mb_ereg_replace: Patterns use the mbstring regular-expression engine and have different delimiter rules from preg_replace().
What Is mb_ereg_replace in PHP?
Replace text matching a multibyte regular expression. Patterns use the mbstring regular-expression engine and have different delimiter rules from preg_replace().
Syntax:
mb_ereg_replace(string $pattern, string $replacement, string $string, ?string $options = null): string|false|null
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: Replacement text and engine-specific backreferences must be checked carefully; avoid assuming PCRE syntax.
Example 1: Basic Usage
This example introduces the operation with a short and predictable input.
<?php
echo mb_ereg_replace("[0-9]+", "#", "Item 123");
The code focuses on the main operation. Patterns use the mbstring regular-expression engine and have different delimiter rules from preg_replace().
Example 2: Another Case
Now compare a different input, locale, date, or option to see another part of the behavior.
<?php
echo mb_ereg_replace("[[:space:]]+", " ", "one two");
What changes? Replacement text and engine-specific backreferences must be checked carefully; avoid assuming PCRE syntax.
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
$incomingLabels = ["order 17", "order 204"];
foreach ($incomingLabels as $label) {
echo mb_ereg_replace("[0-9]+", "[id]", $label) . PHP_EOL;
}
The practical example demonstrates how to apply this operation to multiple values, a reusable task, or a validated input. Patterns use the mbstring regular-expression engine and have different delimiter rules from preg_replace().
Important Behavior and Edge Cases
- Core behavior: Patterns use the mbstring regular-expression engine and have different delimiter rules from preg_replace().
- Inputs and results: Replacement text and engine-specific backreferences must be checked carefully; avoid assuming PCRE syntax.
- Alternatives: preg_replace() uses PCRE and has a separate pattern and replacement syntax.
- Compatibility: mbstring is required for mb_* functions.
Comparison With Related Functions
| Function or Approach | When to Use It |
|---|---|
mb_ereg_replace | Replace text matching a multibyte regular expression. |
| Related PHP approach | preg_replace() uses PCRE and has a separate pattern and replacement syntax. |
Common Beginner Mistakes
| Mistake | Correct Approach |
|---|---|
| Using an incorrect input or option | Replacement text and engine-specific backreferences must be checked carefully; avoid assuming PCRE syntax. |
| Confusing this API with a related operation | preg_replace() uses PCRE and has a separate pattern and replacement syntax. |
| Assuming output is identical across environments | Check return values and required extensions or versions. mbstring is required for mb_* functions. |
Key Takeaways
- mb_ereg_replace helps you replace text matching a multibyte regular expression.
- Patterns use the mbstring regular-expression engine and have different delimiter rules from preg_replace().
- Replacement text and engine-specific backreferences must be checked carefully; avoid assuming PCRE syntax.
Use mb_ereg_replace when you need to replace text matching a multibyte regular expression. 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.