How do I define the starting line for preg_match in PHP?

Question

Im using the preg_match to find a certain word in a text file. However, I want to define the starting line from which preg_match starts its search. How can I make preg_match to ignore the first 5 lines? Additionally, I have a code which will automatically delete the preg_matched word from the file, so im not sure a "start from keyword" would work here.

Heres the code im using.

$contents = file_get_contents($file);
$pattern = preg_quote($searchfor, '/');
$pattern = "/\b$pattern\b/m";
if(preg_match_all($pattern, $contents, $matches))

Better use `file()` to get an array with each line as one entry, then do your regex stuff on index 5 (_ignore the first 5 lines_). — JustOnUnderMillions, Apr 06 '17 at 14:09

score 2 · Accepted Answer · answered Apr 06 '17 at 14:18

Prefixing your pattern with

^((.*)\n){5}\K

should discard the first 5 rows of any search please see the demo below

https://regex101.com/r/wFqazl/2

Your code would then look like this

$contents = file_get_contents($file);
$pattern = preg_quote($searchfor, '/');
$pattern = "/^((.*)\n){5}\K\b$pattern\b/m";
if(preg_match_all($pattern, $contents, $matches))

score 0 · Answer 2 · answered Apr 06 '17 at 14:18

0

I would go this way, like @JustOnUnderMillions suggested

$input = file($file);
$output = array_slice($input, 5); // cut off first 5 lines
$output = implode("\n", $output); // join left lines into one string

// do your preg_* functions on output

answered Apr 06 '17 at 14:18

LiTe

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score 0 · Answer 3 · answered Apr 06 '17 at 14:32

0

If you want to ignore the first 5 lines then

"/^(?:.*?\n){5,5}[^\n]/"

should do it.

https://regex101.com/r/TEBTYt/1

answered Apr 06 '17 at 14:32

GordonM

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How do I define the starting line for preg_match in PHP?

3 Answers3