Hi everyone, and welcome to not only my first tutorial, but my first post entirely. i have a decent programming backround (3 years in C) but this year, i am taking a grade 10 course on Turing. Most people think that turing is a usless language; one you can learn something better, you should. that is really not the case. turing is a fully functional language that can be used for a multitude of things. But, if you are a member of compsci.ca, i'm sure you know that already:D.
I lot of people in my programming class have lots of problems with procedures. this is understandable. They aren't the easiest things to learn, but they aren't the hardest, either. let's start with some sample code.
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% this program asks you your age, and tells you what it is in dog years. var age : int var dog : int put "enter your age: ".. get age dog:=age*7 put "you are ", dog ," years old in dog years." |
This is a VERY simple program. You might have learned about this in your first week on the Turing scene, as it has no scary commands, just put, get, and some math. not a problem. Now, let's make this simple program more complicated then it really needs to be!! Introducing...
THE PROCEDURE!!!
ya. great. so what has it done for me lately?
procedures exist simply to make life easier for programs that are huge. procedures act almost like a loop. you declare that one is going on, you put code into it, and then you end it. now, whenever you call that procedure, it does the code inside it.
Huh?
Let me demonstrate.
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procedure hi put"hello user. how are you today?" end hi hi |
wierd, right? can you guess what the output is? (without looking a few lines below?)
It would look something like this:
Quote:
hello user. how are you today?
great. so what exactly did it do?
It's easy. you made a procedure, and it was named "hi". all it did was say hi to the user. later on, in the bulk of the program, you called it. then, all it did was exactly what was inside of it, namely say hi. then it ended. simple.
procedures like this exist all over turing, all over any language. take 'put' for example. you give it a string, and it displays it on the screen. you have to call it first though, as with any command.
isn't this cool? do you realize what it means???
it means that you can make your own functions. it means that you can make the computer do things that you tell it to do in a nice, clean, way. but wait! there's more...
Procedures have one problem though. what happens if you want your procedure to do math. you get input from the user. but how do you pass that to the procedure? easy. you simple tell it to require parameters.
hmm.... code time!
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var input : int var answer : int procedure doMath (number : int) answer:=number*5 end doMath put"Hi! enter in a number, and i'll multiply it by 5: ".. get input doMath(input) put input," times 5 is ", answer |
cool! what happened?
1. you made a procedure called 'doMath' which required an int as input.
2. you asked the user for input.
3. you called your function with the variable 'input' as the int to be passed.
4. doMath did math.
5. since doMath assigned it's result to a variable called 'answer', you can now use that in your main program, and you do. easy-peasy.
so our first program. how do we optimize that for procedures? you figure it out. then, look below for the answer. if you've got that, then you have procedures down.
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% this program asks you your age, and tells you what it is in dog years. var age : int var dog : int procedure dogYears(AgeToDog : int) dog:=AgeToDog*7 end dogYears put "enter your age: ".. get age put "you are ", dog ," years old in dog years." |
See? procedures are easy. also, as a side note, you can ask for multiple parameters in a procedure, like this:
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procedure doStuff(a,b,c,d : int, blah : string) %stuff would go here end doStuff |
that's all. please, tell me what you all think of my first FAQ!
