preg_replace在字符串中的相同单词

Question

String: this is text :wall: :wall: :wall: :wall: more text

Output should be: this is text :wall: more text

Task: Reduce the word :wall: to only 1.

I tried these both ideas, but didn't work:

$post_message = preg_replace("/([\:wall:])+/", "\\1", $post_message);

$post_message = preg_replace('/:wall:/', '', $post_message, 1);

Answer 1

Use the below regex in preg_replace function.

Regex:

(:wall:)(?:\s+:wall:)+

OR

(:wall:)(?:\s+\1)+

Replacement string:

$1

DEMO

Code:

<?php
$str = "this is text :wall: :wall: :wall: :wall: more text";
echo preg_replace('~(:wall:)(?:\s+\1)+~', '$1', $str);
?>

Output:

this is text :wall: more text

(:wall:) Captures the text :wall: into a group. This could be referred by group index 1. So this (?:\s+\1)+ matches the folowing one or more space + :wall: strings. Replacing the match with the chars inside group index 1 will remove all the duplicate :wall: strings.