perl programing looking for a review

jmc1987 · 10-30-2011, 05:38 PM

Hi! I finally got time to get back to trying to learn perl and I did a number guessing game for practice and understanding and its a exercise to perform out of a book and I was wondering is there far better ways to write this code with only using

if, elsif, else, for, and while statments?

Code:

#!/usr/bin/perl -w

$number=int (rand 10);
print "Pick a number:";
$guess = <STDIN>;
chomp $guess;
while ($guess != $number){
if ($guess>$number){
    print "You guess to high!\n";
    print "Pick a number:";
    $guess = <STDIN>;
    chomp $guess;
    }
        
    elsif ($guess<$number){
        print "You guess to low!\n";
    print "Pick a number:";
    $guess = <STDIN>;
    chomp $guess;
    }}    

    if ($guess== $number) {
        print "You got it right!\n";
    }

Any help is appreciated.

Thanks

Cedrik · 10-30-2011, 05:51 PM

Maybe use an infinite loop, and exit when the user got it right

PHP Code:



#!/usr/bin/perl -w

$number=int (rand 10);

while( 1 ) {
  print "Pick a number:";
  $guess = <STDIN>;
  chomp $guess;

  if ($guess>$number){
    print "You guess to high!\n";
    next;
  }

  if($guess<$number) {
    print "You guess to low!\n";
    next;
  }

  if ($guess== $number) {
    print "You got it right!\n";
    last;
  }
}

jmc1987 · 10-31-2011, 10:37 AM

Very nicely done. I guess the more I learn I'll should be able to figure it out. Thanks

Sergei Steshenko · 10-31-2011, 11:48 AM

Quote:

Originally Posted by jmc1987

Very nicely done. I guess the more I learn I'll should be able to figure it out. Thanks

You code doesn't have

Code:

use strict;

as the very first statement after the interpreter line.

jmc1987 · 11-07-2011, 12:30 PM

I just wanted to give a update. Still working on learning and I was proud to say I actually rewrote it with out looking at the book just using knowledge I learned and I think believe I am progressing but with practice I will get more advanced perl programs.

PHP Code:



#!/usr/bin/perl -w 
 
$number=int (rand 10); 
$guesses=3; 
$wrong=0; 
$guess=(); 
 
while($wrong < $guesses){ 
    print "Pick a Number 1-10."; 
    $guess=<STDIN>; 
    if ($guess != $number){ 
        $wrong++; 
        $chancesleft=$guesses-$wrong; 
        if ($guess < $number){ 
            print "WRONG!\n"; 
            print "You guessed to low! Please guess again!\n"; 
         
        } 
        if ($guess > $number) { 
            print "WRONG!\n"; 
            print "You guessed to high! Please guess again!\n"; 
             
        } 
        print "You have $chancesleft Chances Left!\n\n"; 
         
    } else { 
        print "Great Job!  You Guessed it Right!\n"; 
        exit; 
    } 
} 
print "Thanks for Playing, Better luck next time!\n";

I know its still not much but I'm trying to get it down.

But thanks all for helping. Once I master this I plan to contribute to the Open source community.

Sergei Steshenko · 11-07-2011, 07:17 PM

Quote:

Originally Posted by jmc1987

I just wanted to give a update. Still working on learning and I was proud to say I actually rewrote it with out looking at the book just using knowledge I learned and I think believe I am progressing but with practice I will get more advanced perl programs.

PHP Code:



#!/usr/bin/perl -w 
 
$number=int (rand 10); 
$guesses=3; 
$wrong=0; 
$guess=(); 
 
while($wrong < $guesses){ 
    print "Pick a Number 1-10."; 
    $guess=<STDIN>; 
    if ($guess != $number){ 
        $wrong++; 
        $chancesleft=$guesses-$wrong; 
        if ($guess < $number){ 
            print "WRONG!\n"; 
            print "You guessed to low! Please guess again!\n"; 
         
        } 
        if ($guess > $number) { 
            print "WRONG!\n"; 
            print "You guessed to high! Please guess again!\n"; 
             
        } 
        print "You have $chancesleft Chances Left!\n\n"; 
         
    } else { 
        print "Great Job!  You Guessed it Right!\n"; 
        exit; 
    } 
} 
print "Thanks for Playing, Better luck next time!\n";

I know its still not much but I'm trying to get it down.

But thanks all for helping. Once I master this I plan to contribute to the Open source community.

By not using 'strict' you invite a lot of trouble - which otherwise would have been reported by the compiler. You also program using only global variables - which again is not a good idea.

Realize what 'my' keyword in Perl is for, and what is lexical scoping: http://en.wikipedia.org/wiki/Scope_(programming) .

So far you are making progress in gaining bad programming habits - even if your code works as expected.

jmc1987 · 11-07-2011, 08:04 PM

Yes I am aware of them being global but I was not worried about it considered it is a small program and I don't plan to do further development. But with bigger programs I put variables in blocks. I was just mainly showing that I am writing a bit more cleaner and readable code. But still much room for improvement 1 step at a time. I am going to start using strict though so I does help me build cleaner programs.

sundialsvcs · 11-07-2011, 09:42 PM

Proceed, proceed...

The first computer program I ever wrote was eight lines long (in BASIC), took me six months to write, and had a bug in it.

I learned the craft by writing literally hundreds of programs. I was fascinated (and I still am ...) by how to make a machine do useful things. I'm also pleased to have the opportunity every day to spend time in the company of others who share my same fascination and addiction.

May it never "wear off."

The beauty of computer programming is that there are no "rules." There are plenty of very good guidelines, and lots of war-story experience, but at the end of the day it is just you and the machine. It can go anywhere you can figure out how to take it, and can do anything you can figure out how to make it do. Plus, you can get paid for having fun! (If you don't go crazy first.)

Cedrik · 11-08-2011, 07:17 AM

Quote:

Originally Posted by Sergei Steshenko

You also program using only global variables - which again is not a good idea.

In this program, global variables are adequate though.

Sergei Steshenko · 11-08-2011, 02:59 PM

Quote:

Originally Posted by Cedrik

In this program, global variables are adequate though.

I think I have already written it here - when one "studies" choreography, the tutors do not first teach to dance, they first teach choreographic positions, i.e. how to position hands, feet, shoulders - this is "static"; they teach movements - this is "dynamic", and only then they teach to dance - based on "static" and "dynamic".

My point is that getting rid of bad habits is much more difficult than net acquiring them in the first place.

Cedrik · 11-08-2011, 03:18 PM

Quote:

Originally Posted by Sergei Steshenko

I think I have already written it here - when one "studies" choreography, the tutors do not first teach to dance, they first teach choreographic positions, i.e. how to position hands, feet, shoulders - this is "static"; they teach movements - this is "dynamic", and only then they teach to dance - based on "static" and "dynamic".

My point is that getting rid of bad habits is much more difficult than net acquiring them in the first place.

Just curious, could you re-write this script without any global variable ?

Sergei Steshenko · 11-08-2011, 03:51 PM

Quote:

Originally Posted by Cedrik

Just curious, could you re-write this script without any global variable ?

I can rewrite it with top level lexical variables, and they are different from global ones, e.g. can not be modified by a require'd file.

Also, the actual executable code can be enveloped into a subroutine, and the subroutine can be anonymous, e.g.

Code:

my $do_the_job_sub =
sub
  {
  # actual code goes here
  };

$do_the_job_sub->(); # the job is actually done by this invocation

- since the code is in the subroutine, the variables won't even be top level lexical ones.

The anonymous subroutine can not be overridden - unlike classical named subroutines,

Or the actual executable code can just be enveloped into an additional scope:

Code:

  {
  # actual code goes here
  }

- again, the variables won't even be top level lexical ones.

Cedrik · 11-08-2011, 04:09 PM

Ok, you can

But what would be the advantage of making the data privates in this program ?
I mean, why overcomplicate things when acheiving simple tasks ?

I can see the advantage in larger program where you want to keep each process separate, but here there is not much to do

Sergei Steshenko · 11-08-2011, 04:13 PM

Quote:

Originally Posted by Cedrik

Ok, you can

But what would be the advantage of making the data privates in this program ?
I mean, why overcomplicate things when acheiving simple tasks ?

I can see the advantage in larger program where you want to keep each process separate, but here there is not much to do

As I said, the goal is having the right habits. The amount of global variables should be kept to bear minimum.

Encapsulation is a right habit - not having global variables is the first step on the path to encapsulation.