Multi Threadin in delphi (Access violations)

[vexy]

Hey guys, so I am writing an application that uses Multi threading API.

I keep getting access violation and I have no idea why even when I put a function in the thread that updates the list it gives me access violation after about 4-5 minutes.

What am I doing wrong?

Heres the code:

Top code:

Type
Void = Type Pointer;
var
Form1: TForm1;
t4id, t4h : Cardinal;

in start button:

t4h := CreateThread(nil, 1024, @t4,nil,0,t4id);

In body;

Procedure t4;SafeCall;
var
copyint:integer;
begin
sleep(505);
while True do
begin
sleep(1000);
form1.lstEmails.AddItem('hey4',form1.ssender);
// FetchHTML(getphone,3);
end;
end;

 

[roo0047]

I am writing an application that uses Multi threading API

Why?

Roo
Delphi Rules!

 

[Griffyn]

Read this, and/or be sure you understand this tutorial:

http://www.eonclash.com/Tutorials/Multithreading/MartinHarvey1.1/ToC.html

Rework your code to use Delphi's TThread object. New threads can be added to a project via File, New, Other, Thread Object. menu path for D6).

Post back if you need further help.

 

[AncientHacker]

It's a good idea to use the Delphi TThread object to start up threads instead of the raw system API.

And you should know that the VCL is NOT THREAD SAFE.
Which means you can't willy-nilly call anything in the VCL, even a simple Add(), from a Thread. Well, you can, through the auspices of the Synchronize() method. Look it up.

Another way is to have your thread stuff its data into some global object (interlocking access first ), then have a separate TTimer object processing and posting that data to the VCL.