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Pascal is an imperative, procedural programming language designed by Niklaus Wirth around 1970, named after mathematician Blaise Pascal. It was created to encourage good programming practices using structured programming and strong static typing, and for decades it was a popular teaching language. Pascal emphasizes readability with explicit begin/end blocks, clear type declarations, and a strict compiler that catches many mistakes before a program ever runs.
On CompileBytes, Pascal programs are built with Free Pascal (FPC) version 3.2.2, an open-source, cross-platform compiler that supports the classic Pascal standard along with Object Pascal and Delphi-compatible extensions. It is widely used in education, competitive programming, and legacy maintenance, and ships with a large runtime library. Free Pascal compiles to fast native code, making it suitable for both small learning exercises and larger applications.
main.pas is the entry point for each run.
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program Hello;
begin
writeln('Hello, World!');
end.program Squares;
function Square(n: Integer): Integer;
begin
Square := n * n;
end;
begin
writeln('Square of 5 is ', Square(5));
end.program Counting;
var
i: Integer;
begin
for i := 1 to 5 do
writeln('Count: ', i);
end.program Greet;
var
name: string;
begin
write('Enter your name: ');
readln(name);
writeln('Hello, ', name, '!');
end.program Fact;
function Factorial(n: Integer): Integer;
begin
if n <= 1 then
Factorial := 1
else
Factorial := n * Factorial(n - 1);
end;
begin
writeln(Factorial(6));
end.program SumArray;
var
nums: array[1..5] of Integer = (1, 2, 3, 4, 5);
i, total: Integer;
begin
total := 0;
for i := 1 to 5 do
total := total + nums[i];
writeln('Sum: ', total);
end.program People;
type
Person = record
Name: string;
Age: Integer;
end;
var
p: Person;
begin
p.Name := 'Ada';
p.Age := 36;
writeln(p.Name, ' is ', p.Age);
end.program Countdown;
var
n: Integer;
begin
n := 5;
while n > 0 do
begin
writeln(n);
n := n - 1;
end;
end.program Grade;
var
score: Integer;
begin
score := 2;
case score of
1: writeln('one');
2: writeln('two');
3: writeln('three');
else
writeln('other');
end;
end.The editor uses Monaco, the engine behind VS Code, with language-aware editing tools and familiar keyboard controls.
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Pascal is one of 46 single-file compiler scratchpads. Each run submits only main.pas; local sibling-file imports are not enabled.
Linked-project languages (23): Node.js, TypeScript, Deno, Python, C, Go, Dart, Swift, Rust, Ruby, PHP, Java, Kotlin, C++, C#, Nim, Crystal, Haxe, Zig, Scala, D, Bun, Objective-C.
Single-file scratchpads (46): Matplotlib, NumPy, pandas, Haskell, Clojure, Perl, Lua, Tcl, jq, Raku, Elixir, Bash, Zsh, Nushell, R, Assembly (NASM), Julia, Octave, Groovy, PowerShell, Visual Basic .NET, Odin, Pascal, Lisp, Erlang, CoffeeScript, COBOL, BASIC, V, Racket, OCaml, Prolog, AWK, Emacs Lisp, Emojicode, Forth, F#, Fortran, Assembly (NASM64), Solidity, Mojo, Ada, WASM (WAT), Gleam, Shell Script (sh), Scheme.
Download file exports the active Pascal source file.