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Function?

Blitz3D Forums/Blitz3D Beginners Area/Function?

elseano(Posted 2003) [#1]
Hmmm...
Can't seem to figure out how to use functions.
Could someone please explain it for me?


soja(Posted 2003) [#2]
Do you have a specific question, like what something means? Have you read the manual?

Create a function:
Function duh()
    ...put code here...
End Function

Call it in your main program:
duh()



GameCoder(Posted 2003) [#3]
Ok a function is really quite simple. It stores code that can be accesed from anywhere in the program yo are writing.

example below.


while not keyhit ( 1 )
cls
myfunction()  <<<<This makes a call to myfunction()
flip
wend 
end

Function myfunction() <<<This is the function being called..:)

print "Hello, Im inside a function called myfunction()"

end function



Nebula(Posted 2003) [#4]
Functions make code managable. You can place them in other files(includes) and some editors can fold them(hide them). You can for instance place each part of a program/game inside a function.

Like below. 
intro()
game()
outro()


The entire game would be called in these 3 lines of code, just by using functions. (Not that a game could be made in 3 lines)

Some extra info. Variables inside functions are not global. Every variable will be freed/forgotten when the function is finished.

To return a value from a function you should do :


print addition(10,10)
end

function addition(a,b)
return a+b
end function


Calling the 'Return' alone will exit the function at the point of calling.

Arrays/types and global variables can be accessed and modified from inside a function. You can not create global variables/arrays/types inside functions.

Functions can have predefined arguments.

Function addition(a=0,b=0,c=0,d=0)
return a+b+c+d
end function


Functions can return integers(this is default) Strings(text), or float values(0.42234 ect..)

Function mergestring$(a$,b$)
return a$+b$
End Function

Function Addfloat#(a#,b#)
return a#+b#
End function


You can create Blitz arrays inside functions. They do not have error checking, so do not use these until you know how they work.

Function dostuff(a,b,c,d)
Local stuff[3]

stuff[0] = a
stuff[1] = b
stuff[2] = c
stuff[3] = d

;and ect...

End function


This is all I can come up with at this time. Hit the documentation and look at examples is the best advice
i can give.


jfk EO-11110(Posted 2003) [#5]
most important thing with Functions is when you use a specific Part of Code multiple times then it's better to write a function that can be called as many times as you want.

I guess it was said: Variables n the Main Program (means outside any function) must be defined as Globals if you want to be able to access them inside a Function. Also all Variables you use inside the Function are only Local Variables (unless they are defined as Globals outside the functions), this means their Values are "forgotten" as soon as you end a function.

So to hand over some Variables to a function you can use Globals, or Parameters in the brackets, here the Mouse Position:

setbuffer frontbuffer()
while not keydown(1)
 if mousedown(1)
  drawmouse(mousex(), mousey()) ; << the function call
 endif
wend
end

function drawmouse(x,y)
 plot x,y
end function



elseano(Posted 2003) [#6]
Thanks.
I know it was probably a really stupid question, sorry.


jfk EO-11110(Posted 2003) [#7]
no problem. Docs usually forget to explain fundamental stuff clearly.


CyberPackRat(Posted 2003) [#8]
There are no such thing as stupid questions, just stupid people. Honestly, just kidding.

As I was saying in a previous post, some of us forget what it was like when we first started out and how even the simplest stuff was hard to grasp. So ask away!