user3821320 user3821320 - 4 months ago 14
Perl Question

Perl Term::ReadKey with Arrow Keys

I'm using Term::ReadKey in ReadMode('cbreak') to read a single character and perform an action based on the input. This works fine for all other keys except the arrow keys. When the arrow keys are pressed, the action is performed 3 times and I understand this is because the arrow keys translate to '^[[A', etc...

How do I translate the arrow keys into some arbitrary single value that the ReadKey can interpret?

I tried the following code but it doesn't work:

use Term::ReadKey;

ReadMode('cbreak');

my $keystroke = '';

while ($keystroke ne 'h') {

print "Enter key: ";

#Read user keystroke
$keystroke = ReadKey(0);

chomp($keystroke);


if(ord($keystroke) == 27) {
$keystroke = ('0');
}
}


Here's my code based on the suggestion:

use Term::RawInput;
use strict;
use warnings;

my $keystroke = '';
my $special = '';

while(lc($keystroke) ne 'i' && lc($keystroke) ne 't'){

my $promptp = "Enter key: ";

($keystroke,$special) = rawInput($promptp, 1);

if ($keystroke ne '') {
print "You hit the normal '$keystroke' key\n";
} else {
print "You hit the special '$special' key\n";
}

chomp($keystroke);

$keystroke = lc($keystroke);
}

if($keystroke eq 'i') {
#Do something
}

if($keystroke eq 't') {
#Do something
}


Now, no matter what I press, I can't exit this loop

Here's the output:

Enter key:
Enter key:
Enter key: You hit the normal 't' key

#Proceeds to function

Answer

Here's my working solution...

use Term::ReadKey;

ReadMode('cbreak');

{
    #Temporarily turn off warnings so no messages appear for uninitialized $keystroke
    #that for some reason appears for the if statement
    no warnings;

    my $keystroke = '';

    while ($keystroke ne 'h') {

        print "\nEnter key: ";

        #Read user keystroke 
        $keystroke = ReadKey(0);

        #The first character for the arrow keys (ex. '^[[A') evaluates to 27 so I check for 
        #that
        if(ord($keystroke) == 27) {
            #Flush the rest of the characters from input buffer
            #This produces an 'Use of uninitialized value...' error
            #for the other two characters, hence 'no warnings' at the beginning.
            #This will ignore the other 2 characters and only cause a single iteration
            while( defined ReadKey(-1) ) {}
        }
     }
}