error in <stdin>: use of uninitialised value within %lop in concatenation or string

[saurabhm2623]

the following prog. i was trying but after entering the value alpha or anything generates an error that goes like : use of uninitialised value within %lop in conactenation or string at ...".please help.is there any problem with using the value obtained in scalar via <STDIN>??

use warnings;
use strict;
my $k;
my %lop=(
alpha=>2143,
beta=>456843,
gamma=>78458,
delta=>6453,
theta=>4658);
 
 
$k=<STDIN>;
 
 
 
print"\n $lop{$k}";

[sathishkumar se]

Hi,

Can you try this below code.

use warnings;
use strict;
my $k;
my %lop=(
alpha=>2143,
beta=>456843,
gamma=>78458,
delta=>6453,
theta=>4658);
 
 
$k=<STDIN>;
chomp($k);
 
 
print"\n $lop{$k}";

[Rabbit]

I don't know perl but on line 4 you use %lop but on line 6 you use $lop. Wouldn't they have to be the same? Also you're using different brackets. Do those have to be the same?

[RonB]

The explanation of hashes can get lengthy and confusing, but I'll try to keep it short and simple.

• Hashes are unordered lists of key/value pairs.
• % is the sigil used to denote a hash (as a whole).
• The parens used in the hash assignment indicate list context.
• Within the parens you have a comma separated list of key pairs which are separated by => (known as the fat comma).
• When referring to individual pairs, you use the $ sigil instead of the % sigil and you use the { } braces around the key instead of the parens.

[saurabhm2623]

thanks a lot it solved the problem. but i would like to know what was the mistake in mine. also what did chomp($k) do. (i'm just starting in the basics of perl so dont know much would appreciate your explanation.).

[sathishkumar se]

Hi,

chomp($k);
The above code remove the newline character in the $k variable.