in reply to String validation

Shouldn't that regex also match upper-case letters? Your regex will say that the string "A32g" is bad, but according to the problem description, the original poster wanted to match *any* letters, including (presumably) upper-case. So that string should match. So I would think you could just change that code to: 
if ($string =~ m!(^[A-Za-z0-9]{4})$!) {
    $string =~ tr/[a-z]/[A-Z]/;
    # or $string = uc $string;

    # do something
} else  {
    # do some error
}

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I did a bit of benchmarking of uc vs. tr, and the results were pretty similar: 
Benchmark: timing 1000000 iterations of tr, uc...
        tr: 10 secs ( 7.49 usr  0.00 sys =  7.49 cpu)
        uc:  9 secs ( 6.60 usr  0.00 sys =  6.60 cpu)

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So they should be pretty much interchangeable, in terms of performance.

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You're right...
by chromatic (Archbishop) on Mar 25, 2000 at 02:25 UTC
    Let's make it a little more readable, then: 
    if ($string =~ m!^(\w{4})$!) {
    $string =~ tr/[a-z]/[A-Z]/;
    # or $string = uc $string;
    
    # do something
    } else  {
    # do some error
}

    [download]
    Since the OP wants four alphanumerics (and they are merely *likely* to arrive in lowercase), we'll use \w.

    The reason I suggested using tr/// instead of uc is that, in my testing, uc() failed on a scalar starting with a digit. Now it seems to work correctly. Let's go back to: 

    if ($string =~ s!^(\w{4})$!uc($1)!e) {
    
    # do something
    } else {
    
    # do some error
    # print "Location: $error_url"
}

    [download]
[reply]
[d/l]
[select]
      Do you mean \w? \d just matches digits. I thought of using \w, but \w is alphanumerics plus '_', and I didn't know if the OP wanted '_'.
[reply]

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