My first Ruby script!

[vee-eye]

It gives you the choice of calculating the area of a circle, rectangle, or triangle:

#!/usr/bin/env ruby

# The Area Calculator
# Calculate the area of a variety of shapes

def circle()
 # Get radius
 print "Radius: "
 radius = STDIN.gets
 radius = Float(radius.chop!)

 # Calculate area and print it
 area = 3.14 * radius * radius
 print "The area is ", area, "\n"
 exit
end

def rectangle()
 # Get base and height
 print "Base: "
 base = STDIN.gets
 base = Float(base.chop!)
 print "Height: "
 height = STDIN.gets
 height = Float(height.chop!)

 # Calculate area and print it
 area = base * height
 print "The area is ", area, "\n"
 exit
end

def triangle()
 # Get base and height
 print "Base: "
 base = STDIN.gets
 base = Float(base.chop!)
 print "Height: "
 height = STDIN.gets
 height = Float(height.chop!)

 # Calculate the area and print it
 area = (base * height) / 2
 print "The area is ", area, "\n"
 exit
end

# Start the script

print "Area Calculator!\n\n"
print "Select a shape:\n"
print "1 Circle\n"
print "2 Rectangle\n"
print "3 Triangle\n\n"
print "? "

# Get input - Which shape?
choice = STDIN.gets
# Catch exceptions when input is String or Float - exit
begin
 choice = Integer(choice.chop!)
rescue
 print "Invalid selection\n"
 exit
end

print "\n"

# Calculate the area of the selection
# Catch exceptions when input in area calculations
# is String
begin
 case choice
  when 1
   circle()
  when 2
   rectangle()
  when 3
   triangle()
 end
rescue
end

# This is reached when an exception occurs above
# or when choice does not equal 1, 2, or 3
# Otherwise, the shape functions exit after area calculation
print "Invalid Selection\n"

What do you think? A little sloppy? Should I add more shapes?

By the way, is there a default statement in Ruby (for the case statement)? And does anyone know of any good Ruby tutorials? I found like two of them, and they aren't very... super.

Some general remarks:
- Input: for a string, just do:

print "Enter a string: "
str = gets.chomp

You don't really need the STDIN. Also, prefer chomp to chop: it's safer.

- When you convert from string to float of integer, do something like this:

begin
 num = Float(gets.chomp)
rescue
 puts "Invalid number. Exiting"
 exit 1
end

- You don't need the empty parenthesis if there are no parameters and/or arguments.

- the word puts is the equivalent of print "blah\n". It will change line automatically. Very useful

- You can write a variable like this too:

puts "The value of variable foo is #{foo} and the value of bar is #{bar}"

This is quite helpful IMO.

- The default statement in a case is else

-Tutorial: you are right, there are not so many that are good. But here's one that's pretty good: http://www.ruby-lang.org/~slagell/ruby/index.html

Also, you can find the modules methods here: http://dev.rubycentral.com/ref/


Good luck man, and ask me if you need help. And thanks for not being a wuss and trying Ruby out

Also, here's a small port scanner I made in Ruby (many thanks to jemfinch, I used his algorithm, but it's slower (I can probably fix that)):

#!/usr/bin/env ruby

require 'socket'

if ARGV.length < 2
 puts "Usage: #{$0} <hostname> <highest port to scan>"
 exit 1
end

begin 
 limit = Integer(ARGV[1])
rescue
 puts "Error: port number must be an integer"
 exit 1
end

for x in 1 .. limit
 begin
  t = TCPSocket.new(ARGV[0], x)
 rescue
  next
 end
 puts "#{x} is open"
 t.close
end

[vee-eye]

Those are some sweet hints, man! *Now I don't have to do print "Hello, World!\n" anymore. *I was wondering why you were using puts instead of print all the time.

And thanks for the tip on gets. *I was looking for a shortcut like str = STDIN.gets.chomp, but that obviously wouldn't work.

Should I use chomp or chomp! ? *And why is it safer than chop! ?

I'm looking forward to reading that tutorial. Thanks.

Methods that end with an exclamation (!) are applied to the object. So:

irb(main):001:0> a = "Hello\n"
"Hello\n"
irb(main):003:0> a.chomp
"Hello"
irb(main):004:0> a
"Hello\n"
irb(main):005:0> a.chomp!
"Hello"
irb(main):006:0> a
"Hello"
irb(main):007:0>

I don't know if you understand? And chomp removes the "\n" (with no arguments), while chop removes the last character:

irb(main):007:0> b = "Hello"
"Hello"
irb(main):008:0> b.chop!
"Hell"
irb(main):009:0>

[vee-eye]

I understand now. Thanks, you're a big help.

No problem. I've been advocating Ruby for the 6 past months and you're the first one who's interested.

[Feztaa]

Hey, I was interested, I'm just busy.

Yeah, yeah right ;D

No problem. I've been advocating Ruby for the 6 past months and you're the first one who's interested.

K.... I cave... I'll try it out - any good links to learn this stuff ?

btw. It looks so damn c00l, please do a PET series on ruby scripting.