String Replace/Switch Question

[theflyingminstr]

Hi, I want to switch two numbers, but when I try to do it within an array a little bit too much switching is happening and I'm not yielding the end result I'm looking for.

<?php

$rawstring = "Replace 1 with 3, and 3 with 1.";

$placeholders = array('1', '3');

$replvals = array('3', '1');

$newstr = str_replace($placeholders, $replvals, $rawstring);

echo $newstr;

?>

Thanks so much.

[JAY6390]

PHP Code:

<?php

$rawstring = "Replace 1 with 3, and 3 with 1.";
$newstr = preg_replace('/\b(1|3)\b/', '[$1]', $rawstring);
$placeholders = array('[1]', '[3]');
$replvals = array('3', '1');
$newstr = str_replace($placeholders, $replvals, $newstr);
echo $newstr;

[theflyingminstr]

Amazing, thanks so much!

[JAY6390]

no problem

[kbluhm]

PHP Code:

function str_swap( $string, Array $replacements = array() )
{
    if ( ! empty( $replacements ) )
    {
        $search  = array_keys( $replacements );
        $replace = array_values( $replacements );
        foreach ( $search as $i => $value )
        {
            $string = str_replace( $value, '[[' . $i . ']]', $string );
        }
        foreach ( $replace as $i => $value )
        {
            $string = str_replace( '[[' . $i . ']]', $value, $string );
        }
    }
    return $string;
}

// echoes: Replace 3 with 1, and 1 with 3.
echo str_swap( 'Replace 1 with 3, and 3 with 1.', array( 1 => 3, 3 => 1 ) ); 


You can exchange the brackets for something more unique to ensure the changes are made properly. If [[0]], etc, already exists in the original string (rare but possible) it would throw the whole thing off.

[JAY6390]

I did consider the possibility of that, but the example looked so simple I didn't think it would matter

[MattF]

Nothing like a good bit of overkill chaps.

$string = "Replace 1 with 3, and 3 with 1.";
$string = str_replace(array('1', '3'), array('3', '1'), $string);

print($string);

[JAY6390]

That produces
Replace 1 with 1, and 1 with 1. which is why the examples above had the tags

[MattF]

Oops. Duly chastised.

[theflyingminstr]

I like the logic of the function a lot. Thanks kbluhm.