Re^2: Capture a non-printable char and test what it is

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Re^3: Capture a non-printable char and test what it is by haukex (Archbishop) on May 22, 2022 at 04:41 UTC
Where do you find that? kcott is right that I simply looked at the code's output, but it's also documented in Quote and Quote like Operators. If I look at the ascii table I see that the escape key can be represented as: 27 (decimal), 1B (hexadecimal), 033 (octal). Those work too: the string `"\e"` is the same as `"\x1B"` and `"\033"` - you can try this out yourself with `eq`.	[reply] [d/l] [select]
Re^4: Capture a non-printable char and test what it is by almsdealer (Acolyte) on May 22, 2022 at 17:15 UTC
Thank you, that link to quote-like characters is very useful. I think one mistake I made was trying to test if the char was the hex value of the escape key using single quotes.	[reply]
Re^5: Capture a non-printable char and test what it is by kcott (Archbishop) on May 23, 2022 at 07:32 UTC
In the time-honoured tradition of TMTOWTDI, if you replace `if ( $key eq "\e" ) { print "Escape pressed\n"; }` [download] with `if ( $key eq "\e" && $key eq "\x1b" && $key eq "\033" && $key eq "\c[" && $key eq "\x{1b}" && $key eq "\o{33}" && $key eq "\N{ESCAPE}" && $key eq "\N{U+001B}" && $key eq v27 && ord($key) == 27 && ord($key) == 0x1b && ord($key) == 033 && ord($key) == 0o33 && ord($key) == 0b11011 ) { print "Escape pressed\n"; }` [download] you'll get the same result. I don't claim that's a non-exhaustive list of all possibilities, but I think it's pretty close. You can find references to all of those in one or more of: perlop; perldata; perlrebackslash. — Ken	[reply] [d/l] [select]
Re^6: Capture a non-printable char and test what it is by afoken (Chancellor) on May 23, 2022 at 22:10 UTC
Re^7: Capture a non-printable char and test what it is by kcott (Archbishop) on May 24, 2022 at 00:25 UTC
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Re^3: Capture a non-printable char and test what it is by kcott (Archbishop) on May 22, 2022 at 03:26 UTC
"How does \e represent the escape key? Where do you find that?" If you'd bothered to run the short piece of code ++haukex provided, and pressed the escape key, you would have seen: `Press a key $VAR1 = "\e"; Escape pressed` [download] Had you pressed the enter key: `Press a key $VAR1 = "\n";` [download] I suggest you also read ++haj's post for additional information and alternative methods to use. — Ken	[reply] [d/l] [select]
Re^4: Capture a non-printable char and test what it is by almsdealer (Acolyte) on May 22, 2022 at 17:13 UTC
Yes, my mistake. I see that now.	[reply]
Re^3: Capture a non-printable char and test what it is by cavac (Parson) on May 24, 2022 at 14:56 UTC
If I look at the ascii table then you only see a part of the non-printable characters available on modern computer systems. Unicode has more control characters, emoji skin tone modifiers, right-to-left mark and a host of other stuff that is unprintable on it's own. As an additional bonus, the same character on screen can sometimes be encoded in Unicode in multiple ways, see Unicode equivalence. Unfortunately, input processing has gotten a tad more complex since the world gave up on ye olde ASCII table. On the bright side, these days more than the 20% of world population of the old ASCII days can now type their name into a computer with a reasonable expectation that it will be processed correctly. `perl -e 'use Crypt::Digest::SHA256 qw[sha256_hex]; print substr(sha256_hex("the Answer To Life, The Universe And Everything"), 6, 2), "\n";'`	[reply] [d/l]
Re^4: Capture a non-printable char and test what it is by kcott (Archbishop) on May 25, 2022 at 06:34 UTC
I generally agree with everything you've written there; however, as a minor nitpick, those skin tone modifiers can be printed in isolation. I'm not sure how this will render on different browsers, but on my terminal: $ perl -C -E ' say for "\N{U+1F3FB}", "\N{U+1F3FC}", "\N{U+1F3FD}", "\N{U+1F3FE}", "\N{U+1F3FF}" ' 🏻 🏼 🏽 🏾 🏿 And, in a preview, that looks fine on my Firefox v100.0.2 — YMMV. — Ken	[reply]
Re^5: Capture a non-printable char and test what it is by cavac (Parson) on May 25, 2022 at 08:13 UTC
You are right, those are printable when used standalone. Which makes them sometimes-printable-characters. Great, another exception that has to be handled when working with text. `You are in the hallways of the text processing convention. To the sout +h, you see someone selling T-Shirts, to the north is the building exit. The entrance to the lecture hall is to the west. > complain about unicode cavac raises his fist to the gods and shouts "UNICODE!!!". H��r shoots + cavac in the buttocks with a mistletoe arrow.` [download] `perl -e 'use Crypt::Digest::SHA256 qw[sha256_hex]; print substr(sha256_hex("the Answer To Life, The Universe And Everything"), 6, 2), "\n";'`	[reply] [d/l] [select]


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