Regular string expression

[wahoyaho 0]

How can I make it check that there's only 1 of a certain character and removes all the rest?

So for example if only one character "a" is allowed a string of

test1atest2atest3

would become

test1atest2test3

Edited November 27, 2007 by wahoyaho

[wahoyaho 0]

Anyone know?

[picaxe 1]

Not using regexp, but this will do it

$string = "test1atest2atest3"
$find = "a"
$first = StringInStr($string, $find)
If $first > 0 Then
    $result = StringReplace($string, $find, "")
    $result = StringLeft($result, $first - 1) & $find & StringRight($result, StringLen($result) - $first + 1)
    MsgBox(0, "", $result)
EndIf