how to replace everything after a hyphen symbol

[lindajames]

hi, i have the following code

<?
echo $content;
?>

The above code produces outputs in the following format:

121212-Description

Can anyone tell me how i can use a replace function to replace everything after the "-" sign with a ":" sign

thank you

[coopster]

everything?

$content = '121212-Description'; 
$content = substr_replace [php.net]($content, ':', strpos [php.net]($content, '-'));