Change the value of an variable in a function

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Dark Basic Pro X Collision

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Joined: 20th Sep 2007

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Posted: 9th Jul 2014 01:50

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Hi there.

If I have a variable in my main-program that I wish to change inside a function. What is the best way for me to do this?
I have looked into global variables but I can't get it to work.

What I would like to know is if the following programs could be translated to DBPro. If not, maybe someone could be nice and write me an example of how to change a global variable in a function.

In C I would write it like this
void multiplyWithFour(int *a)
{
*a=*a*4;
}
int main()
{
int a = 2;
multiplyWithFour(&a);
printf("%d",a);//This would print 8
}

Does DBPro support pointers?

Or can you maybe return a value from a function?
Like this (In C) :

int multiplyWithFour(int a)
{
return a*4;
}
int main()
{
int a=2;
a=mutiplyWithFour(a);
printf("%d",a);//This line will also print 8
}

Thanks!

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Dark Basic Pro X Collision

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Posted: 9th Jul 2014 03:31 Edited at: 9th Jul 2014 04:25

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I created a dummy sphere and used the coordinates as global variables. The coordinates can be changed and read from inside the functions. Altough I would prefer to use pointers or a function that returns a value...

+ Code Snippet

make object sphere 1,0,0,0
number#=4
position object sphere 1,number#,0,0
multiplyWithFour()
number#=object position x(1)
print $number
wait key
end

function multiplyWithFour()
   number#=object position x(1)
   position object 1,number#*4,0,0
endfunction

I haven't tested the code above, but I think you will get the picture

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Dark Basic Pro X Collision

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Posted: 9th Jul 2014 04:39 Edited at: 9th Jul 2014 04:51

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Found this:
http://forum.thegamecreators.com/?m=forum_view&t=192789&b=1

And this:
http://forum.thegamecreators.com/?m=forum_view&t=87472&b=7

Perfect!

I should have looked a little more before I posted this thread

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WickedX

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Posted: 9th Jul 2014 11:14 Edited at: 9th Jul 2014 11:16

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To return a single value you can do something like this. You have probable figured this out from TDK's tutorial.

+ Code Snippet

a = 2
a = multiplyWithFour(a)
print a

wait key

end

function multiplyWithFour(a as integer)
   a=a*4
   ` return a;
endfunction a

You could also use the make memory function and pass the DWORD address of the memory allocated to the function. But, for returning an objects position or rotation, I would use the 3D-Math vector3 functions. Just pass the vector3 ID to the function. No return parameter required.

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