When you need to return a string portion beginning at a case-insensitive match, it helps to understand both the normal result and what changes with different inputs. This guide focuses on practical examples rather than repeating PHP background material.
grapheme_stristr provides the behavior described below. A grapheme cluster is a user-perceived character, potentially consisting of more than one Unicode code point.
What Is grapheme_stristr in PHP?
Return a string portion beginning at a case-insensitive match. A grapheme cluster is a user-perceived character, potentially consisting of more than one Unicode code point.
Its syntax is:
grapheme_stristr(...)
Parameters and return value: Read the argument names and optional values in the signature above. Methods use an existing object, while stand-alone functions take direct arguments. The examples demonstrate the relevant arguments and the value returned or the object modified.
Important: This returns a substring, not a numeric offset. The optional before-needle flag reverses the selected portion.
Example 1: Basic Usage
This first example demonstrates how to return a string portion beginning at a case-insensitive match with a small input.
<?php
var_dump(grapheme_stristr("Hello World", "world"));
The example uses the simplest useful form. A grapheme cluster is a user-perceived character, potentially consisting of more than one Unicode code point. The output may depend on the active ICU locale, PHP configuration, or input supplied to the function.
Example 2: Another Case
Here the input or option changes, making it easier to see where the behavior differs. This returns a substring, not a numeric offset. The optional before-needle flag reverses the selected portion.
<?php
var_dump(grapheme_stristr("Résumé Guide", "GUIDE", true));
Compare the result to the first example. Use strlen() for bytes, mb_* for code points and grapheme_* for grapheme clusters.
Practical Example: Applying the Function
This standalone example shows how the same operation fits into a small application task. The intl extension is required for this example.
<?php
$subject = "Topic: PHP Arrays";
$result = grapheme_stristr($subject, "php");
if ($result !== false) { echo $result; }
The example keeps the operation visible and gives you a starting point for using it in an application. This returns a substring, not a numeric offset. The optional before-needle flag reverses the selected portion.
Important Behavior and Edge Cases
- Core behavior: A grapheme cluster is a user-perceived character, potentially consisting of more than one Unicode code point.
- Return value: Check the result separately from changes to passed-in arrays, iterators, or object state.
- Data constraints: This returns a substring, not a numeric offset. The optional before-needle flag reverses the selected portion.
- Environment: The intl extension is required for this example.
Comparison With Related Functions
| Function or Approach | When to Use It |
|---|---|
grapheme_stristr | Return a string portion beginning at a case-insensitive match. |
| Related PHP APIs | Use strlen() for bytes, mb_* for code points and grapheme_* for grapheme clusters. |
Common Beginner Mistakes
| Mistake | Correct Approach |
|---|---|
| Assuming the function works on every kind of input | Follow the declared argument types and check the input format before calling it. |
| Ignoring the behavior of the result | This returns a substring, not a numeric offset. The optional before-needle flag reverses the selected portion. |
| Using the wrong related PHP API | Use strlen() for bytes, mb_* for code points and grapheme_* for grapheme clusters. |
Key Takeaways
grapheme_stristrhelps you return a string portion beginning at a case-insensitive match.- A grapheme cluster is a user-perceived character, potentially consisting of more than one Unicode code point.
- This returns a substring, not a numeric offset. The optional before-needle flag reverses the selected portion.
- Use strlen() for bytes, mb_* for code points and grapheme_* for grapheme clusters.
grapheme_stristr is useful when you need to return a string portion beginning at a case-insensitive match. Start with the small examples, then adapt the practical example while respecting its input and environment requirements.