Single replace using RegEx

gbudiman

Hi,
I'm having a hard time doing single-replace (as opposed-to multiple replace) using preg_replace

This is the string that I want to replace:

A F C7 D

I want them to be replaced to:

F C# G#7 A#

My function is $output = preg_replace($search, $replace, $string);
where $search is an Array ( [0] => A [1] => F [2] => C7 [3] => D )
and $replace is an Array ( [0] => F [1] => C# [2] => G#7 [3] => A# )

However, using the function above will yield the result:

C# C# G#7 A#

The letter A is replaced with F, and then replaced again with C#, which is not what I want. I want each letter to be replaced only once. How do I accomplish that?

Thanks

NogDog

This approach seems to work, though I wouldn't be surprised if there was a cleaner way.

$search = array('/(?<!@)A/', '/(?<!@)F/', '/(?<!@)C/', '/(?<!@)D/');
$replace = array('@F', '@C#', '@G#', '@A#');
$chords = "A F C7 D";
$transposed = str_replace('@', '', preg_replace($search, $replace, $chords));
echo $chords . "<br />" . $transposed;

nrg_alpha

I'm not sure if I'm on the right path or not, but would strtr() not be a good viable solution?

$str = 'A F C7 D';
$chordReplace = array('A'=>'F', 'F'=>'C#', 'C7'=>'G#7', 'D'=>'A#');
$str = strtr($str, $chordReplace);
echo $str;

EDIT - Granted, I'm assuming the A F C7 D string is by itself and not imbedded within a block of text (the OP doesn't specify the context in which those letters are used).