Get line number from preg_match_all()

Question

I\'m using PHP\'s preg_match_all() to search a string imported using file_get_contents(). The regex returns matches but I would like to know at which line number those matches a

Answer 1

This works but performs a new preg_match_all on every line which could be quite expensive.

$file = file.txt;

$log = array();

$line = 0;

$pattern = '/\x20{2,}/';

if(is_readable($file)){

    $handle = fopen($file, 'rb');

    if ($handle) {

        while (($subject = fgets($handle)) !== false) {

            $line++;

            if(preg_match_all ( $pattern,  $subject, $matches)){

                $log[] = array(
                    'str' => $subject, 
                    'file' =>  realpath($file),
                    'line' => $line,
                    'matches' => $matches,
                );
            } 
        }
        if (!feof($handle)) {
            echo "Error: unexpected fgets() fail\n";
        }
        fclose($handle);
    }
}

Alternatively you could read the file once yo get the line numbers and then perform the preg_match_all on the entire file and catpure the match offsets.

$file = 'file.txt';
$length = 0;
$pattern = '/\x20{2,}/';
$lines = array(0);

if(is_readable($file)){

    $handle = fopen($file, 'rb');

    if ($handle) {

        $subject = "";

        while (($line = fgets($handle)) !== false) {

            $subject .= $line;
            $lines[] = strlen($subject);
        }
        if (!feof($handle)) {
            echo "Error: unexpected fgets() fail\n";
        }
        fclose($handle);

        if($subject && preg_match_all ( $pattern, $subject, $matches, PREG_OFFSET_CAPTURE)){

            reset($lines);

            foreach ($matches[0] as $key => $value) {

                while( list($line, $length) = each($lines)){ // continues where we left off

                    if($value[1] < $length){

                        echo "match is on line: " . $line;

                        break; //break out of while loop;
                    }
                }
            }
        }
    }
}}