How to Efficiently Search a String for Multiple Patterns Using an Array in PHP?

How to Search a String for Multiple Patterns Using an Array

The strpos function is a powerful tool for searching for a specific substring within a string. However, it can only search for a single pattern at a time. What if you need to check if a string contains any of a list of patterns?

Consider the following example:

$find_letters = ['a', 'c', 'd'];
$string = 'abcdefg';

If we attempt to search the string for the array of letters using strpos, it will not work. This is because strpos expects a string as its second argument, not an array.

Creating a Function for Array Search with strpos

To solve this problem, we can create a custom function that accepts an array of patterns and a string to be searched. The function will iterate through the array, calling strpos for each pattern, and return the position of the first match found:

function strposa(string $haystack, array $needles, int $offset = 0): bool
{
    foreach ($needles as $needle) {
        if (strpos($haystack, $needle, $offset) !== false) {
            return true; // stop on first true result
        }
    }
    return false;
}

This function can be used as follows:

$string = 'This string contains word "cheese" and "tea".';
$array = ['burger', 'melon', 'cheese', 'milk'];
var_dump(strposa($string, $array)); // will return true, since "cheese" has been found

Conclusion

By creating a custom function that wraps the strpos functionality, we can now efficiently search a string for multiple patterns using an array. This technique can be useful in a variety of scenarios, such as validating user input or performing text analysis.

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