The mb_eregi() function is an inbuilt function in PHP that performs case-insensitive regular expression matches on a string having multibyte support. If the string pattern is matched, then it will return the string otherwise it will return false.

Syntax:

mb_eregi(
    string $pattern, 
    string $string, 
    array &$matches = null
): bool

Parameters: The following function has three parameters that are described below.

• $pattern: The regular expression pattern that we used for matching against the multibyte string.
• $string: This is the string where we search our pattern.
• $matches: This is the parameter that stores the matched substrings which starts from the left parentheses from the $string input. $matches[1] will have the matched substring which starts at the first left parentheses and $matches[2] will have the matched substring which starts at the second left parentheses and so on.

Return Values: The mb_eregi() function returns a boolean value after executing the case insensitive regular expression. If the function found the pattern in the given string, it will return “true”, otherwise it will return “false”.

Program 1: The following program demonstrates the mb_eregi() function.

Pattern found!

Program 2: The following program demonstrates the mb_eregi() function.

Match not found!

Reference: https://www.php.net/manual/en/function.mb-eregi.php