Question

I just answered a question here, which has left me asking my own question.

Basically, the OP wanted any line to be removed if it contained a string. Here is a regex I came up with…

$str = preg_replace('/^.*\b["(]?hello["(]?\b.*$/m', '', $str);

It works great, but because $ matches before the trailing \n, they remain when replaced and there are blank lines, e.g.

string(90) "
What it shouldhello do is:


could be words in between brackets and inverted commas also."

I can’t use \z because I’m in multiline mode (at least that is what I think).

If I use s modifier, the . become too greedy and don’t work across the newlines.

I have tried a few things (such as [^\n] and [\s\S]), and now I am stumped.

How can I match that trailing \n here so it is removed with the replace?

Answer 1

Use \n instead of $.

$str = preg_replace('/^.*\b["(]?hello["(]?\b.*\n/m', '', $str);

This misses the last line if it had hello in it, so here’s a step further.

$str = preg_replace('/^.*\b["(]?hello["(]?\b.*(\n|$)/m', '', $str);

The issue now is that the last line is removed, but there is still a \n character (similar issue you’re already having).

Note: I’m not a regular expression expert at all, just can usually do enough for my needs.