Pointers

BlitzMax Forums/BlitzMax Programming/Pointers

Leiden

(Posted 2006) [#1]

Playing around with pointers, why wont this work. Can pointers only be basic object types? e.g. int, float, etc. Is it not possible to create a type ptr?

Type test
End Type

Local t:test = New test
Local p:test Ptr = Varptr t

This seems to work, but is it the only way?

Type test
	Field i:Int = 100
End Type

Local t:test = New test
t.i = 10

Local p:Int Ptr
Local i = HandleFromObject(t)

p = Varptr i
Local n:test = test(HandleToObject(p[0]))
Print n.i

ImaginaryHuman

(Posted 2006) [#2]

Varptr has to have the () in order to return a value, ie local p:test ptr=varptr(t)

Leiden

(Posted 2006) [#3]

It still says "Illegal Pointer Type" on the last line of the first example. I was more wondering why you cant have pointers to Blitzmax types. I've settled for using a TList and dumping the result to an array and indexing the array just like you would a traditional C pointer. Seems to work well without the overhead of the TList when reading results back.

SculptureOfSoul

(Posted 2006) [#4]

The reason you can't have a pointer to a Blitzmax type is because Blitzmax types are already "by reference."

So, if you want p to be a pointer to t, you can do the following

global t:test = new test
global p:test = t  '<---p now points to the same object as t

Any changes made to p are of course reflected in t, and the opposite is true as well.