Creating a Dynamic Array referencing a Class Object

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2 total messages Started by Nick DeLallo Sun, 13 Jul 2008 21:09

#44

Author: Nick DeLallo
Date: Sun, 13 Jul 2008 21:09

10 lines
1144 bytes

I define a dynamic array of Unit2.TestClassExample;

XClassEx : array of Unit2.TclassExample;  // okay
//xClassEx := unit2.TClassExample(self);  // does not work
setlength(xclassEx,100);                  // okay 

// add to the array I get an access error
// How do I initialize the array.
// TclassExample is a record containing variable data

Re: Creating a Dynamic Array referencing a Class Object

#46

Author: Warren Postma
Date: Fri, 18 Jul 2008 13:25

26 lines
1752 bytes

Nick DeLallo wrote:
> I define a dynamic array of Unit2.TestClassExample;
>
> XClassEx : array of Unit2.TclassExample;  // okay
> //xClassEx := unit2.TClassExample(self);  // does not work
> setlength(xclassEx,100);                  // okay 
>
> // add to the array I get an access error
> // How do I initialize the array.
> // TclassExample is a record containing variable data
>
>
>   
Probably TclassExample is not a record, it's a class. You need to 
understand the difference between a record and a class.

The main thing to remember about Class types is that declaring one is 
not enough, you must also construct it.

var
  Foo: Array of TMyClass
begin
    SetLength(Foo,10);
   /// Foo[0] := TMyClass.Create;  // if we don't do this first...
    Foo[0].property1 := 10;   // ... then we get an Access violation!
end;

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