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PHP string replace match whole word

Posted by: admin April 23, 2020 Leave a comment


I would like to replace just complete words using php

Example :
If I have

$text = "Hello hellol hello, Helloz";

and I use

$newtext = str_replace("Hello",'NEW',$text);

The new text should look like

NEW hello1 hello, Helloz

PHP returns

NEW hello1 hello, NEWz


How to&Answers:

You want to use regular expressions. The \b matches a word boundary.

$text = preg_replace('/\bHello\b/', 'NEW', $text);

If $text contains UTF-8 text, you’ll have to add the Unicode modifier “u”, so that non-latin characters are not misinterpreted as word boundaries:

$text = preg_replace('/\bHello\b/u', 'NEW', $text);


multiple word in string replaced by this

    $String = 'Team Members are committed to delivering quality service for all buyers and sellers.';
    echo $String;
    echo "<br>";
    $String = preg_replace(array('/\bTeam\b/','/\bfor\b/','/\ball\b/'),array('Our','to','both'),$String);
    echo $String;
    Result: Our Members are committed to delivering quality service to both buyers and sellers.


Array replacement list: In case your replacement strings are substituting each other, you need preg_replace_callback.

$pairs = ["one"=>"two", "two"=>"three", "three"=>"one"];

$r = preg_replace_callback(
    "/\w+/",                           # only match whole words
    function($m) use ($pairs) {
        if (isset($pairs[$m[0]])) {     # optional: strtolower
            return $pairs[$m[0]];      
        else {
            return $m[0];              # keep unreplaced

Obviously / for efficiency /\w+/ could be replaced with a key-list /\b(one|two|three)\b/i.


You can also use T-Regx library, that quotes $ or \ characters while replacing

$text = pattern('\bHello\b')->replace($text)->all()->with('NEW');