What does the error message "Unknown modifier 'I'" indicate in the context of preg_grep usage?

The error message "Unknown modifier 'I'" indicates that the 'I' modifier is not recognized by the preg_grep function in PHP. This modifier is typically used for case-insensitive matching, but it seems to be causing an issue in this context. To solve this problem, you can remove the 'I' modifier from the regular expression pattern being used in preg_grep. 

// Incorrect usage with 'I' modifier causing error
$pattern = '/example/i';
$array = ['Example', 'example', 'EXAMPLE'];
$matches = preg_grep($pattern, $array);

// Corrected code without 'I' modifier
$pattern = '/example/';
$array = ['Example', 'example', 'EXAMPLE'];
$matches = preg_grep($pattern, $array, PREG_GREP_INVERT);

Keywords

preg_grep PHP error message Unknown modifier 'I'

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