PHP Removing multiple whole lines from text file

Question

I am using str_replace to remove certain string that starts with the '#' character from a read txt file, however the html output when tested removes only the # symbol. The problem I am having is that I want to remove all of the text beginning with that particular character (including '#' too).

So far I have tried:

1)

$data = str_replace('#','',file_get_contents($strFileName));
return $data;

2)

fopen($strFileName,'r');
$remove = "#";
$tmpData = file_get_contents($strFileName);
$data = preg_replace("/.*\b" . $remove ."\b.*\n/ui", "#"  , $tmpData);
return $data;

The original text file is like this:

#

# bla bla bla 

#

# bla bla bla 

#

# bla bla bla

The first try did remove the # character but left the rest of the words. The second didn't work at all. Thanks.

Related: https://stackoverflow.com/q/28830850/2943403 – mickmackusa Jan 30 '22 at 08:18 — mickmackusa, Jan 30 '22 at 08:18

score 1 · Accepted Answer · answered Dec 11 '16 at 11:56

1

You can do that with preg_replace,

$data = preg_replace("/^#.*/m", "", $tmpData);

answered Dec 11 '16 at 11:56

Federkun

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Perfect, many thanks. Any hint on how to remove the line when the comment is indented? For instance the "#comment bla bla" is indented and the above expression does not detect it. Thanks – ASO Dec 11 '16 at 12:37
Add `\s`: `$data = preg_replace("/^\s*?#.*/m", "", $tmpData);` – Federkun Dec 11 '16 at 12:39

Alon Adler · Answer 2 · 2016-12-11T12:10:00.900

You indeed need to use preg_replace for replacing the #. But you need to "tell" the regex that you are processing a multi-line text, so it wont stop the replacement after the first line. You do that by applying the m modifier in the end of the regular expression pattern, so the pattern sent to preg_replace will be:

/^#.*/m - note the m in the end of the expression, which means: multiline search

This will match the following: a single # char at line start (as ^ is the line start identifier) and all the line afterwards. With the below replacment:

$data = preg_replace('/^#.*/m','',$tmpData);

Will replace the whole lines which were matched above with nothing.

Here is a working example.

PHP Removing multiple whole lines from text file

2 Answers2