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Bug #75172 $replace_pairs can't be used instead of $to and $from
Submitted: 2017-09-08 10:25 UTC Modified: 2017-09-08 10:33 UTC
From: hyman dot omg at gmail dot com Assigned:
Status: Not a bug Package: Strings related
PHP Version: 5.6.31 OS: centos6.5
Private report: No CVE-ID: None
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 [2017-09-08 10:25 UTC] hyman dot omg at gmail dot com 
Description:
------------
In PHP Manual,we can find the message "The replace_pairs parameter may be used instead of to and from, in which case it's an array in the form array('from' => 'to', ...)".In fast,the results are different,it doesn't work as documented.

Test script:
---------------
<?php
    $str = 'I loved you';
    $from = 'love';
    $to = 'lOvE';
    var_dump($result1 = strtr($str, $from, $to));//I lOvEd yOu
    var_dump($result2 = strtr($str, [$from=>$to]));//I lOvEd you
    var_dump($result1===$result2);//false

Expected result:
----------------
I lOvEd you
I lOvEd you
true

Actual result:
--------------
I lOvEd yOu
I lOvEd you
false

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 [2017-09-08 10:33 UTC] requinix@php.net
-Status: Open +Status: Not a bug
 [2017-09-08 10:33 UTC] requinix@php.net 
Thank you for taking the time to write to us, but this is not
a bug. Please double-check the documentation available at
http://www.php.net/manual/ and the instructions on how to report
a bug at http://bugs.php.net/how-to-report.php

Please read all the docs, not just parts of it.

> If given three arguments, this function returns a copy of str where all
> occurrences of each (single-byte) character in from have been translated to the
> corresponding character in to

> If given two arguments, the second should be an array in the form array('from'
> => 'to', ...). The return value is a string where all the occurrences of the
> array keys have been replaced by the corresponding values.

That is, strtr has two different behaviors: character replacement by passing two strings or string replacement by passing one array.
 [2017-09-08 10:33 UTC] kelunik@php.net 
These are replace pairs, see https://3v4l.org/3rfuV

<?php

$str = 'I loved you';
$from = 'love';
$to = 'lOvE';

var_dump($result1 = strtr($str, $from, $to));
var_dump($result2 = strtr($str, [$from[0] => $to[0], $from[1] => $to[1], $from[2] => $to[2], $from[3] => $to[3]]));
var_dump($result2 = strtr($str, [$from => $to]));
var_dump($result1===$result2);//false
 [2017-09-08 10:33 UTC] mail at pmmaga dot net 
You are misreading the docs. It states:

> If given three arguments, this function returns a copy of str where all occurrences of each (single-byte) character in from have been translated to the corresponding character in to.

It says, "of each character". So all your lowercase "o" and "e" will be uppercased in your example.
 
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