EAccessViolation in function CreateProcess in Delphi 2009

很有趣的，我也遇到了這件事情，明明 CreateProcess 這函式在Delphi 7時就正常，到了Delphi 2009就出怪手了。

原因就是出在Unicode……解法轉貼如下：

The problem is in the lpCommandLine parameter. I suspect you are doing something like this:

var
  CmdLine: string;
...
CmdLine := 'notepad.exe';
CreateProcess(nil, PChar(CmdLine), ...)

This results in an access violation because CmdLine is not writeable memory. The string is a constant string stored in read-only memory.

Instead you can do this:

CmdLine := 'notepad.exe';
UniqueString(CmdLine);
CreateProcess(nil, PChar(CmdLine), ...)

This is enough to make CmdLine be backed by writeable memory.

It is not enough just to make the variable holding the string non-const, you need to make the memory that backs the string writeable too. When you assign a string literal to a string variable, the string variable points at read-only memory.

參考來源：Access Violation in function CreateProcess in Delphi 2009