在PHP中替换标点符号周围的空格

Question

I'm trying to replace trailing spaces around punctuation marks in PHP with matched punctuation followed by a single space.

For example "Hello , I am here ! Not anymore. .. " should become "Hello, I am here! Not anymore... " . I'm trying to use a regular expressions with a reference

PHP

$string = preg_replace('/\s*[[:punct:]]\s*/', '$2 ', $string);

But the snippet removes punctuations: "Hello I am here Not anymore" .
What am I missing?

Answer 1

This should work for you:

<?php

    $string = "Hello  , I am here   ! Not anymore. ..  ";
    echo $string = preg_replace('/(\s*)([[:punct:]])(\s*)/', '$2 ', $string);

?>

Output:

Hello, I am here! Not anymore. . .

Answer 2

You don't capture anything and then you try to replace with the second capture group that doesn't exist. Try a capture group () and then use it $1 :

$string = preg_replace('/\s*([[:punct:]])\s*/', '$1 ', $string);

Answer 3

In order to substitute . . . . . . with ... , this is what I'd do:

$string = "Hello  , I am here   ! Not anymore. . .  ";
$string = preg_replace('/\s+(?=\pP)|(?<=\pP\s)\s+/', '', $string);
echo $string;

Output:

Hello, I am here! Not anymore...

\\pP is the unicode property for punctuation, see the doc .
(?= ) is a positive look ahead
and (?<= ) a positive look behind, see the doc .