字母之间只允许一个空格

Question

I don't know almost anything about regex, but I need to allow only one space between letters, this is what I have done with another questiona and answer, plus random tries with regex101:

/^(\d){1,}(\:[A-Za-z0-9-]+([ a-zA-Z0-9-]+)?)?\:(\d){1,}(?:\.(\d){1,2})?$/m

The fomat should be:

[integer]:[optional label :][integer/decimal]

Example:

12:aaa:12.31
56:a s f:15
34:45.8

I have done some random tries without any success,I'm only able to allow infinite space, could someone help me? I have also looked at others answers, but I couldn't implement in my regex.

Check if error:

    preg_match_all('/^(\d+)(:[A-Z0-9-]+(?: [A-Z0-9-]+)*)?:(\d+(?:\.\d{1,2})?)$/mi', $_POST['ratetable'], $out);
    if($out[0]!=explode("
",$_POST['ratetable'])){
        header('Content-Type: application/json; charset=utf-8');
        echo json_encode(array(0=>'Invalid price table at line: '.implode(", ", array_diff_key(array_flip(explode("
",$_POST['ratetable'])),array_flip($out[0])))));
        exit();
    }

Answer 1

You could make the regex a bit shorter and allow a single space in between each letter like this:

/^(\d+)(:[A-Z0-9-]+(?: [A-Z0-9-]+)*)?:(\d+(?:\.\d{1,2})?)$/gmi

regex101 demo

If you want to capture only the label (and exclude the :) in the capture, you can use this one.