Delphi: Execute external Program and pass Parameters

After I have shown how to start another program out of your Delphi application in this tipp, I would like to show you now, how to pass parameters to the external application.

I would like to show you 2 alternatives for this.

Alternative 1: WinExec

The function WinExec comes with a small number of parameters:

WinExec('C:\prog.exe param1 param2', SW_SHOW);

Here, we are starting the program "C:\prog.exe" and we are passing the parameters "param1" and "param2" to the program. So, as a first parameter, we are passing the command line and as a second parameter, we can define how the program should be displayed.

Alternative 2: ShellExecute

But it is also possible to pass parameters by using the ShellExecute function. Here is the same example carried out with the help of ShellExecute:

uses ShellApi;
var parameter: String;

parameter:='param1 param2';

ShellExecute(0, 'open', 'C:\prog.exe', PChar(parameter), nil, SW_SHOW);

Important: When passing a string as parameter, we have to use PChar() before.