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Hello, World!

How would you like to do your Hello World?

Using the Lazarus IDE

Note

This section assumes you have correctly set up the following for your OS.

  1. The Free Pascal Compiler.
  2. The Lazarus IDE.

Create a Project

  1. Launch Lazarus IDE.
  2. Create a new Project.
    • On the top menu bar, click Project -> Simple Program -> OK.
  3. Save this Project.
    • Click Project -> Save Project.
    • Save the Project file as HelloWorld.lpi in a new folder.
    • Note: Lazarus will save the main source file as HelloWorld.lpr.

You will see a simple program in the Source Editor window. The program's name will be the same as the Project's name, as shown below.

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program HelloWorld;

begin
end.

Add Code

  1. Now insert the following lines between begin and end..
WriteLn('Hello, World!');
ReadLn; // Add this to pause the program and see the output
  • The WriteLn function prints text on the console.
  • The ReadLn waits for you to press Enter, keeping the console window open so you can see the "Hello, World!" message.
  1. Add the following compiler directives after the program declaration. 
{$mode objfpc}{$H+}{$J-}

Note

This line {$mode objfpc}{$H+}{$J-} is a common setup for Free Pascal projects. It tells the compiler to use modern Object Pascal features and settings. It's good practice to include it.

Your final code would look as follows.

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program HelloWorld;

{$mode objfpc}{$H+}{$J-} // Add this line in your object pascal codes.

begin
  WriteLn('Hello, World!');
  ReadLn;
end.
  1. Press Ctrl+S to save the code.

Compile & Run

Press F9 to compile and run the program.

You should be able to see a console window open with Hello, World! displayed.

Lazarus IDE: Press the Enter key to exit the program, which also closes the console.

Using the CLI

Note

This section assumes you have correctly set up the Free Pascal Compiler and the fpc is in your PATH.

Create a .pas File & Add Code

  1. Launch your favourite text editor.
  2. Create a new file and put the following snippet in it.
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program HelloWorldCLI; // It's good practice to name your program
{$mode objfpc}{$H+}{$J-} 

begin
    WriteLn('Hello, World!');
    ReadLn; // Add this to pause the program and see the output
end.
  1. Save it as HelloWorld.pas.

Compile & Run

Windows CLI

On Windows, compile and run as follows.

> fpc HelloWorld.pas && HelloWorld.exe

Tip

If running fpc from the Command Prompt (CLI) doesn't work, here are a few things to check:

  1. Full Path: Try using the full path to fpc.exe (e.g., C:\FPC\3.2.2\bin\i386-win32\fpc.exe HelloWorld.pas).
  2. PATH Variable: Ensure the directory containing fpc.exe (e.g., C:\FPC\3.2.2\bin\i386-win32\) is added to your system's PATH environment variable. You might need to restart your Command Prompt after updating PATH.
  3. Lazarus IDE: If CLI is tricky, using the Lazarus IDE (as shown above) is often easier for beginners.
  4. VSCode/VSCodium Users: If you're using VSCode or VSCodium, make sure the Pascal extension by Alessandro Fragnani is set up correctly to find the compiler.
  5. OmniPascal: For a more integrated VSCode experience, you might also look into OmniPascal.

Linux CLI

On Linux, compile and run as follows.

$ fpc HelloWorld.pas && ./HelloWorld