equivalent of the default variable doesn't work - perl

Question

I have a simple server application written in Perl. Here's the working version of it.
my $client;
while ($client = $local->accept() ) {
print "Connected: ", $client->peerhost(), ":", $client->peerport(), "\n";
while (<$client>) {
if ($mod_ctr == -1) {
$num_count = $_;
init();
}
elsif ($mod_sayaci % 2 == 0) {
$plus_count = $_;
}
elsif ($mod_sayaci % 2 == 1) {
$minus_count = $_;
eval();
}
last if m/^q/gi;
$mod_sayaci++;
}
print "Server awaits..\n";
}
I'm positive this works perfectly. Now, When I change my code to take a starting char from the client to determine the operation instead of using mod:
my $client;
while ($client = $local->accept() ) {
print "Connected: ", $client->peerhost(), ":", $client->peerport(), "\n";
$input;
$operation;
$value;
while ($input = <$client>) {
$operation = substr($input, 0, 1);
$value = substr($input, 1, 1);
print "input: $input \n";
print "operation: $operation \n";
print "value: $value \n";
if ($operation == "r") {
print "entered r \n";
$num_count = $value;
init();
}
elsif ($operation == "a") {
print "entered a \n";
$plus_count = $value;
}
elsif ($operation == "e") {
print "entered e \n";
$minus_count = $value;
eval();
}
elsif ($operation == "q") {
# will quit here
}
}
print "Server awaits..\n";
}
At the client side, I make the user start with the request which sends r as operation. Everything works fine until now. After the first input, input, operation and value prints work fine, but it always enters the first if and prints entered r. What am I missing here?

Answer 1

You have changed from using numbers to using strings to dictate which of the branches should be executed. You need to use eq instead of == to do string comparisons.
Like this
if ($operation eq "r") {
print "entered r\n";
$num_count = $value;
init();
}
etc.
Also, you would be doing yourself and anyone who helps you a big favour if you added
use strict;
use warnings;
to the top of every Perl program you write. The "declarations"
$input;
$operation;
$value;
don't do anything useful except as a comment to say which variables are used within the block. Write this
my ($input, $operation, $value);
and you have done something much more useful.