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Language: Pascal
Expertise: Beginner

Feb 22, 1999

Question:
What code do I use for Delphi to run a program and use command line parameters inputted by the user?

Answer:
This code will allow you to launch other applications from your own. To use this function, simply supply a fully qualified path name in ProgramName and any arguments on the command line following the program name separated by a space. As the help file states: "If lpApplicationName is NULL, the first white space-delimited token of the command line specifies the module name..." In English, the characters before the first space encountered (or if no space is encountered as in a single program call) is interpreted as the EXE to execute. The rest of the string is the argument line.

procedure ExecNewProcess(ProgramName : String);
var
  StartInfo  : TStartupInfo;
  ProcInfo   : TProcessInformation;
  CreateOK   : Boolean;
begin

  { fill with known state }
  FillChar(StartInfo,SizeOf(TStartupInfo),#0);
  FillChar(ProcInfo,SizeOf(TProcessInformation),#0);
  StartInfo.cb := SizeOf(TStartupInfo);

  CreateOK := CreateProcess(nil, PChar(ProgramName), nil, nil,False,
              CREATE_NEW_PROCESS_GROUP+NORMAL_PRIORITY_CLASS, 
              nil, nil, StartInfo, ProcInfo);

  { check to see if successful }
  if CreateOK then
    //may or may not be needed. Usually wait for child processes
    WaitForSingleObject(ProcInfo.hProcess, INFINITE);
end;

For example, let's say that the user inputted: "/a /b /c" as command line arguments, and you captured them into a string var called "args." To use ExecNewProcess, you'd simply do this:

MyProgramName := 'C:\Program Files\MyProgram\MyProgram.EXE';
ExecNewProcess(MyProgramName + ' ' + args);

Pretty simple...