I think he was assuming you were working in a UNIX environment, where 'ruby calc.rb' would look in the PATH for 'ruby' and then run it with the argument 'calc.rb'.

Not sure how that would work in Windows. Does Windows even have a global path? Try going "Start->Run" and putting "ruby calc.rb" there... ionno. Check the documentation of wherever you installed the ruby interpreter/compiler.

I did typed that in run just now and it flashed a black windows but nothing happened.

Which version of Windows are you using?

For Win 98, ME:

Go to Start -> Run, and type "command". This will give you a command prompt. You'll need to "cd" (change directory) to the directory where you saved calc.rb.

For Win 2000, XP:

Go to Start -> Run, and type "cmd". This will give you a command prompt. You'll need to "cd" (change directory) to the directory where you saved calc.rb.

I dont have a clue about commands. I saved it to my E drive so i went cd E:\ but i know thats wrong. Im running Win XP Pro SP2.

Ah. To change directories...

code:

C:\Whatever\Yada\Yada> E: E:\> cd "the directory\where\I\saved\the file" E:\the directory\where\I\saved\the file> ruby calc.rb

Is this right so far?? I dont think it is because i got an error.

E:\>cd ruby calc.rb\E

The system cannot find the path specified.

Should look something like that. Learning how to use the command-line is key to learning how to program.

You don't want to cd to the file itself, just the directory it's in.

Consider if I start out in C:\ and I have calc.rb saved in E:\Programming\Ruby\

code:

C:\> E: E:\> cd "Programming\Ruby" E:\Programming\Ruby>

Now I'm in the right directory.

code:

E:\Programming\Ruby> ruby calc.rb

My next set of Ruby questions will be in this topic. At the rate im going i probably wont get nothing done..

Just remember.. one step at a time. Make sure you understand each idea before going on to the next. The author of a tutorial will assume you do.

Fine with me. Just give me some time to reply. I'm writing an introduction/tutorial on Python's generators and iterators.

Ok... Numbers.

Any questions here?

Have you got irb open? If you do, you should see a prompt like:

code:

irb(main):001:0>

well first. I have it open but didnt write anything in there. I dont know what to write at that line so how can i know whats going on?? Its not my fault i was born to learn slow..

I typed "puts 1 + 2" at the prompt and hit enter in the above example.

The "1 + 2" part takes two numbers and adds them together. Not surprisingly, the result is 3.

The "puts" takes that result and prints it out.

"=> nil" shows the result of "puts". In this case it's basically "nothing".

And then you see the prompt again, ready for the next thing.

Ok yes im ready.. will i learn Ruby tonight or will it take sometime??

I can't really say. It's doubtful you'll learn all of the basics in one night, especially approaching it without prior experience (I tackled Ruby already knowing several languages, so my experience is going to be different from yours).

I think you could get all of the basics in a week or two. Of course, there's a lot more there beyond the basics, but that's true of any programming language.

code:

irb(main):002:0> puts 5 * (12-8) + -15 5 => nil irb(main):003:0>

Do you understand what's going on here?

I'm only 24, young'en.

And congrats, but limit the profanity. We don't want school filters restricting access to this site.

Now, write a line of code which displays the number of seconds in a year.

No offense but are you on drugs?

my god. I dont know that much math or how to do it. go smoke another one.

How many seconds are in a minute?

How many minutes are in an hour?

How many hours are in a day?

How many days are in a year?

How many seconds are in a minute?

How many minutes are in an hour?

How many hours are in a day?

How many days are in a year?

there are 60 minutes in an hour
there are 24 hours in a day
there are 365 days in a year. So i would be like this??

60 * 24 * 365
525600

That's the number of minutes in a year.... so just multiply by the number of seconds in a minute and you have the number of seconds in a year.

Now, convert it to Ruby code. (Hint: You're 99% of the way there already)

Hint: note what happens when you run the following in irb.

code:

puts 5 * 4 * 2

Good.

Moving on...

Do you know why 4 is different from 4.0?

Not really.

code:

4

Is an integer. It's a whole number.

code:

4.0

Is a floating point number. It has a decimal part in addition to a whole number.

Integers are generally more useful. We mostly consider 1, 2, 3, etc. "things", rather than halves of "things".

For the most part, Ruby handles the differences between integers and floats pretty transparently, but the difference does show up in math.

When you do math between two integers, the result is always another integer. But introduce a single float into the mix and the result is a float.

code:

3 / 2

Is 1.

code:

3 / 2.0

Is 1.5.

Does this make sense?

Do you understand what a string is?

A string is a sequence of characters.

code:

"Hello world!"

Is a string. Strings are enclosed in either double quotes, as above, or in single quotes. There are slight differences between them, but generally you can use the interchangeably in simple examples.

Make sense?

On to string math.

You can use + and * on strings as well as numbers.

code:

"foo" + "bar"

is

code:

"foobar"

and, since...

code:

4 * 3

is just

code:

4 + 4 + 4

then

code:

"foo" * 3

is just

code:

"foo" + "foo" + "foo"

Which is

code:

"foofoofoo"

Any questions?

You should be trying these in irb as we go.

Ah, you've struck on an interesting point.

code:

"3"

Is a string that contains the character 3.

code:

3

Is an actual number.

In something like:

code:

"4" * 3

The * is expecting the next "thing" to be a number. Similarly, "4" + 3 won't work, because the + is expecting another string.

Strings can be converted to numbers, and vice-versa... but first, does the above make sense?

In programming, we commonly deal with different types of data. Remember that word. You'll hear it so many times it'll eventually drive you mad.

Follow along, young padawan.

Err... excuse me. I'm quite insane, you see, and you have to make allowances for my flights of fancy.

Anyway, we deal with different types of data. So far we've seen three of them.

• Integers - whole numbers. 1, 2, 3 etc. But not 1.23, 2.6, 4.2, etc.
  
• Floats - numbers that can have a decimal component. The catch is that they aren't always 100% accurate once you start dealing with really really big numbers.
  
• Strings - sequences of letters, numbers, etc.

The pattern when we "concatenate" (add) strings is:

string + string

And the pattern when you multiply strings is:

string * integer or float

If you use a float in that one, it just uses the whole number part.

So...

code:

"hello " * 3.5

Is

code:

"hello hello hello "

Just to make sure, you've been trying these on your own and seeing the right answers, right?

Did you see what you expected to?

Sweet.

More about "puts". We can look at this and think it's just the english word "puts", but what it really is, is put string.

So:

code:

puts 42

Is really:

code:

puts 42.to_s

But you don't need to type out the ".to_s".

So, if "puts" is put string, can you guess what "gets" means, and what it does?

Nifty... so now you get input from the user.

Time to learn how to create files and run those.

Do you know how to change directories in DOS?

Did you save the file at the root of your C drive?

Nono, what he means is that first you have to cd into the directory with the .rb file in it. So if the .rb file is in "C:\Documents\Programming\Ruby\" then type:

code:

cd c: cd Documents cd Programming cd Ruby ruby greet.rb

Or, if you're feeling adventurous,

code:

cd c:\Documents\Programming\Ruby\ ruby greet.rb

If it's already IN root C;\ and that's where you are by defult, you don't need to cd anywhere. Just: ruby greet.rb

Ok... the file is obviously not in C:\, so trying to run it from there will not work.

Where exactly did you save the file? Use the search feature if you have to.

Is it really "greet.rb", or did it get saved as "greet.rb.txt"?

Ok... not gonna give up on this.

Try "type greet.rb" at the command-line. The Windows command prompt, not the IRB prompt.

ok.. here is a different error message down below..

greet.rb:3: syntax error
puts "Hello, " + Derek "!"

Cool.

You're missing a + between Derek and "!".

The name of the variable should also be "name".

Spiffy.

Now, do you understand why the program went something like:

code:

C:\> ruby greet.rb And your name is? Derek Hello, Derek ! C:\>

When it should have looked like:

code:

C:\> ruby greet.rb And your name is? Derek Hello, Derek! C:\>

Sure.

When you call "gets" to get input from the user, you get all of their input, including the return key.

Then, then you use "puts" to output, you get that return again.

The key is to use another method named "chomp" to remove the return from the end of that string.

code:

puts "And your name is?" name = gets.chomp puts "Hello, " + name + "!"

Post the code you write. Please surround it with code tags, like so:

code:

[code]This is formatted as code.[/code]

Select the text normally with your mouse. DOS-style applications are a bit weird about selecting text. Start at the top-left corner and drag down to the bottom right corner.

While the text is selected, right-click. Congratulations. You just copied test the DOS way.

Right-click again in a DOS-style app to paste.

In a normal program, just paste normally.

It will NOT let me copy it from the command window..

well i found out how to copy it from edit greet.rb from start-->> Run-->>cmd but now can figure out how to paste it to this board. when i right clicked on this board its not pasting my output..

Just right-click and select "Paste".

Ok, there are various steps to solving this problem.

• Ask for the person's first name
  
• Get their first name and store it in a variable
  
• Ask for their middle name
  
• Get that name and store it in a variable
  
• Ask for their last name
  
• Store that name in a variable
  
• Say hello, concatenating (adding) their first, middle, and last names into one name

The problem you're having with the code you pasted is that you don't quite seem to understand the purpose of a variable. A variable is just a convenient name for a piece of data.

The variable in the code you pasted was "name". When you add together the strings in the last line of code, use that variable name.

code:

puts "John R. Doe?" name = gets puts "Hello " + name + "!"

You'll have to type something and hit enter before the program should terminate.

OK i got it.

Now, do you see what I was saying about "!" ending up on a new line?

Ummm... i have another question. Do i use the SciTE to program? Because when i save it, it saves as like some unkown file type, not a ruby program. But i installed it properly and everything because the sample programs work.