tr///

[Paul Morris]

Hi all

I found this at:

http://www.suse.com/us/private/support/howto/secprog/secprog8.html

...but am having difficulty working it out, because it doesn't seem to 
do what I think it should (and "I" may be the problem!).

To quote:
--------------------
The best solution is to select a filter for Perl, just like for shell, 
which only accepts authorized characters.

unless($userinput =~ tr/[EMAIL PROTECTED]//)
{
    print "Nice try, pal!\n";
    exit(1);
}
--------------------
I know the tranliteration search string is duplicated as the replacement 
string, and that the tr will return the number of changes made - it's 
just that I can't see how, if the input string DOES contain valid 
characters AND invalid characters, that the 'unless' will ever be entered.

This is my implementation of the above:
---------------
use strict;
$inputString = "&[EMAIL PROTECTED]";
print $inputString;
print "\n";
unless ($inputString =~ tr/[EMAIL PROTECTED]//){
print "Gotcha!";
}
print $inputString;
---------------
Despite having NO characters replaced, the condition is not entered...

Any thoughts?

Thanks, Paul

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