User input in perl - Issue with running script in KomodoEdit

Question

i wrote this tiny code on gedit and ran it :-

#/usr/bin/perl
print "Enter the radius of circle: \n";
$radius = <>;
chomp $radius;
print "radius is: $radius\n";
$circumference = (2*3.141592654) * $radius;
print "Circumference of circle with radius : $radius = $circumference\n";

Runs fine using command line.Ran the same code on Komodo Edit: facing an issue i expect first line as output as :- Enter the radius of circle: whearas it waits on the screen i.e waiting for an input and after that runs everything in sequence -- can someone tell me why it runs fine with command line but not Komodo?

---

output after changing #/usr/bin/perl to #!/usr/bin/perl:- also had to declare my $radius and my $circumference ----------------------------------------------------------

12 # same i had to enter 12
Enter the radius of circle: 
radius is: 12
Circumference of circle with radius : 12 = 75.398223696

Answer 1

I have tested your script using Komodo edit and it works fine other then below few corrections.

#!/usr/bin/perl -w
use strict;

print "Enter the radius of circle: \n";
my $radius = <>;
chomp $radius;
print "radius is: $radius\n";
my $circumference = (2*3.141592654) * $radius;
print "Circumference of circle with radius : $radius = $circumference\n";

Output in Komodo

Enter the radius of circle: 
5
radius is: 5
Circumference of circle with radius : 5 = 31.41592654

Answer 2

While 'use strict' and a correctly spelled shebang line are always good things, neither is the actual cause. When you run an interactive program in a non-command-line environment, you should usually turn off I/O buffering. In Perl you should put this line at the top of your code:

$| = 1;