Delphi/Lazarus: Command Line Parameter Tutorial Part 1: Sending

In this little tutorial, I want to show you, how you can pass commands or parameters from the command line or via batch files to your Delphi or Lazarus application, to then evaluate these commands or parameters in your program.

In this first part, we will first look at how to send parameters to the program, in the second part, we will see, how to receive and process the parameters.

Command Line

If you call the program from the command line, you can simply pass the parameters after the call of the program, for example:

C:\Delphi>MyApplication.exe param1 param2

With this call we pass two parameters to the program "MyApplication.exe". The first parameter consists of the text "param1", the second parameter of the text "param2". Parameters are separated with spaces. If a parameter should contain spaces itself, we have to write the parameter in quotation marks, such as "param 1".

Batch Script

It is also very simple, if you use a batch file or any other type of script to invoke your program. In this case, you can simply write the parameters like in the command line behind the program file:

@echo off
start /wait MyApplication.exe param1 param2

With this method you can also create different BAT files for the different parameter constellations for testing or calling  the same program with different settings.

Delphi IDE

To start the program directly from the Delphi IDE with parameters, you can go in the menu to "Run > Parameters". Here, you can enter the parameters, with which the program is started directly after compiling from Delphi. Just type "param1 param2" in the field to pass "param1" and "param2" through the IDE.

Of course, this call directly using the IDE is very useful in the development phase, because that way, you do not always have to start the program after compiling from the command line to try it out. Of course, the data passed through the IDE parameters remain independent of the program itself, they will not be compiled into the program.

Lazarus IDE

Also if we work with Lazarus, we can store parameters in the IDE with which our program is started out of the IDE after compiling. The settings for this can be found in the menu "Run > Run Parameters > Command Line Parameters". In this dialog you will also find some other settings for parameters and environmental variables with which the program should be executed and you can define different modes with which you can save and call up frequently used parameter constellations.

Part 2: Receive parameters

In the second part of the command line tutorial, we will look at how to receive and process the parameters from the command line in the program.