PHP Function: stristr

In PHP, the stristr function is a powerful tool that allows developers to search for a specific substring within a given string, regardless of the case sensitivity. This function is particularly useful when working with user input or when manipulating strings in various applications.

Syntax

The syntax for the stristr function is as follows:

stristr(string $haystack, mixed $needle, bool $before_needle = false): string|false

The stristr function takes three parameters:

• $haystack: The string to search within.
• $needle: The substring to search for.
• $before_needle (optional): If set to true, the function returns the part of the haystack before the first occurrence of the needle. If set to false (default), the function returns the part of the haystack from the first occurrence of the needle onwards.

Return Value

The stristr function returns the portion of the haystack string starting from the first occurrence of the needle and up to the end of the string. If the needle is not found, the function returns false.

Example Usage

Let's explore some examples to understand how the stristr function works:

$string = "Hello, World!";
$substring = "world";

$result = stristr($string, $substring);
echo $result; // Output: "World!"

In this example, the stristr function successfully finds the substring "world" within the haystack string "Hello, World!" and returns the portion of the string starting from the first occurrence of the substring.

$string = "Hello, World!";
$substring = "WORLD";

$result = stristr($string, $substring);
echo $result; // Output: "World!"

Even though the needle is in uppercase, the stristr function is case-insensitive by default. It still successfully finds the substring "WORLD" within the haystack string "Hello, World!" and returns the portion of the string starting from the first occurrence of the substring.

$string = "Hello, World!";
$substring = "WORLD";

$result = stristr($string, $substring, true);
echo $result; // Output: "Hello, "

By setting the third parameter to true, the stristr function returns the portion of the haystack string before the first occurrence of the needle. In this example, it returns "Hello, ".

Summary

The stristr function in PHP is a versatile tool for searching and manipulating strings. It allows developers to find substrings within a given string, regardless of case sensitivity. By understanding how to use this function effectively, developers can enhance their string manipulation capabilities and create more robust applications.

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