pascal.md

Pascal Programming with Time Warp Studio

Pascal is a structured programming language known for emphasizing clarity and structure. Time Warp Studio provides experimental Pascal support for learning procedural programming concepts.

Quick Start

A simple Pascal program:

program HelloWorld;
begin
  WriteLn('Hello, World!');
end.

Run this:

1. Select "Pascal" from the language dropdown
2. Paste the code
3. Click Run (Ctrl+R)

Basic Syntax

Program Structure

program ProgramName;

var
  { Variable declarations }

begin
  { Program statements }
end.

Comments

{ This is a comment }
(* This is also a comment *)

Variables and Data Types

var
  age: Integer;
  height: Real;
  initial: Char;
  is_student: Boolean;
  name: String;

Data Types:

• Integer - Whole numbers
• Real - Decimal numbers
• Char - Single character
• String - Text
• Boolean - True/False

Output: WriteLn

program OutputDemo;
begin
  WriteLn('Hello, World!');
  WriteLn('Age: ', 25);
  WriteLn('Height: ', 5.9:3:1);  { value:width:decimals }
end.

Input: ReadLn

program InputDemo;
var
  name: String;
  age: Integer;
begin
  Write('Enter your name: ');
  ReadLn(name);
  Write('Enter your age: ');
  ReadLn(age);
  WriteLn('Hello, ', name, ' (age ', age, ')');
end.

Operators

Arithmetic

var
  a, b, sum, diff, product, quotient: Integer;
begin
  a := 10;
  b := 3;
  
  sum := a + b;        { 13 }
  diff := a - b;       { 7 }
  product := a * b;    { 30 }
  quotient := a div b; { 3 (integer division) }
end.

Note: Use := for assignment (not =)

Comparison

if x = 10 then WriteLn('Equal');
if x <> 5 then WriteLn('Not equal');
if x > 5 then WriteLn('Greater');
if x < 20 then WriteLn('Less');
if x >= 10 then WriteLn('Greater or equal');
if x <= 15 then WriteLn('Less or equal');

Logical

if (age >= 18) and (is_student) then
  WriteLn('Adult student');

if (age < 18) or (is_student) then
  WriteLn('Young or student');

if not (is_student) then
  WriteLn('Not a student');

Control Flow

if/else

program GradeCalculator;
var
  score: Integer;
begin
  Write('Enter score: ');
  ReadLn(score);
  
  if score >= 90 then
    WriteLn('Grade: A')
  else if score >= 80 then
    WriteLn('Grade: B')
  else if score >= 70 then
    WriteLn('Grade: C')
  else
    WriteLn('Grade: F');
end.

case Statement

program CaseExample;
var
  choice: Integer;
begin
  Write('Choose (1-3): ');
  ReadLn(choice);
  
  case choice of
    1: WriteLn('Option 1');
    2: WriteLn('Option 2');
    3: WriteLn('Option 3');
    else WriteLn('Invalid option');
  end;
end.

Loops

for loop:

var
  i: Integer;
begin
  for i := 1 to 5 do
    WriteLn('Number: ', i);
end.

Counting backwards:

for i := 5 downto 1 do
  WriteLn('Countdown: ', i);

while loop:

var
  count: Integer;
begin
  count := 0;
  while count < 5 do
  begin
    WriteLn('Count: ', count);
    count := count + 1;
  end;
end.

repeat...until loop:

var
  count: Integer;
begin
  count := 0;
  repeat
    WriteLn('Count: ', count);
    count := count + 1;
  until count >= 5;
end.

Procedures and Functions

Procedure

procedure Greet(name: String);
begin
  WriteLn('Hello, ', name, '!');
end;

begin
  Greet('Alice');
  Greet('Bob');
end.

Function

function Add(a, b: Integer): Integer;
begin
  Add := a + b;
end;

var
  result: Integer;
begin
  result := Add(3, 5);
  WriteLn('Result: ', result);
end.

Procedures with Multiple Parameters

procedure PrintInfo(name: String; age: Integer; city: String);
begin
  WriteLn('Name: ', name);
  WriteLn('Age: ', age);
  WriteLn('City: ', city);
end;

begin
  PrintInfo('Alice', 25, 'New York');
end.

Arrays

One-Dimensional Array

var
  numbers: array[1..5] of Integer;
  i: Integer;
begin
  numbers[1] := 10;
  numbers[2] := 20;
  numbers[3] := 30;
  
  for i := 1 to 5 do
    WriteLn('numbers[', i, '] = ', numbers[i]);
end.

String Array

var
  names: array[1..3] of String;
  i: Integer;
begin
  names[1] := 'Alice';
  names[2] := 'Bob';
  names[3] := 'Charlie';
  
  for i := 1 to 3 do
    WriteLn('Name: ', names[i]);
end.

Complete Example Programs

Simple Calculator

program Calculator;
var
  a, b: Real;
  op: Char;
  result: Real;
begin
  WriteLn('=== Simple Calculator ===');
  Write('Enter first number: ');
  ReadLn(a);
  Write('Enter operator (+, -, *, /): ');
  ReadLn(op);
  Write('Enter second number: ');
  ReadLn(b);
  
  case op of
    '+': result := a + b;
    '-': result := a - b;
    '*': result := a * b;
    '/': begin
           if b <> 0 then
             result := a / b
           else
           begin
             WriteLn('Error: Division by zero');
             exit;
           end;
         end;
    else WriteLn('Invalid operator');
  end;
  
  WriteLn('Result: ', result:5:2);
end.

Number Guessing Game

program GuessingGame;
var
  secret, guess, attempts: Integer;
begin
  WriteLn('=== Guessing Game ===');
  secret := 42;
  attempts := 0;
  
  repeat
    Write('Guess the number (1-100): ');
    ReadLn(guess);
    attempts := attempts + 1;
    
    if guess < secret then
      WriteLn('Too low!')
    else if guess > secret then
      WriteLn('Too high!')
    else
    begin
      WriteLn('Correct! You guessed it in ', attempts, ' attempts!');
      break;
    end;
  until guess = secret;
end.

Multiplication Table

program MultiplicationTable;
var
  n, i, j: Integer;
begin
  WriteLn('=== Multiplication Table ===');
  Write('Enter table size: ');
  ReadLn(n);
  WriteLn;
  
  for i := 1 to n do
  begin
    for j := 1 to n do
      Write(i*j:4, ' ');
    WriteLn;
  end;
end.

Sum and Average

program SumAverage;
var
  numbers: array[1..10] of Integer;
  sum, count, i: Integer;
  average: Real;
begin
  WriteLn('=== Sum and Average ===');
  Write('How many numbers? ');
  ReadLn(count);
  
  for i := 1 to count do
  begin
    Write('Enter number ', i, ': ');
    ReadLn(numbers[i]);
  end;
  
  sum := 0;
  for i := 1 to count do
    sum := sum + numbers[i];
  
  average := sum / count;
  WriteLn;
  WriteLn('Sum: ', sum);
  WriteLn('Average: ', average:5:2);
end.

Tips and Best Practices

1. Use descriptive names: age is better than a
2. Comment complex logic: Explain how it works
3. Break code into procedures: Keep procedures small
4. Test thoroughly: Try edge cases
5. Use proper spacing: Make code readable

Common Mistakes to Avoid

{ ❌ Wrong: Using = for assignment }
age = 25;

{ ✅ Right: Use := for assignment }
age := 25;

{ ❌ Wrong: Forgetting semicolon }
WriteLn('Hello')
WriteLn('World');

{ ✅ Right: Semicolons between statements }
WriteLn('Hello');
WriteLn('World');

{ ❌ Wrong: Array indices out of bounds }
var numbers: array[1..5] of Integer;
numbers[10] := 5;  { Error! }

{ ✅ Right: Stay within bounds }
numbers[5] := 5;

Pascal vs. Other Languages

Feature	Pascal	C	Python
Assignment	:=	=	=
Output	WriteLn	printf	print
Input	ReadLn	scanf	input
Comments	{ } or (* *)	/* */ or //	# or """ """
Procedures	procedure	void function	def
Functions	function	return_type function	def

Learning Resources

• Start Simple: Begin with I/O programs
• Use Comments: Document your learning process
• Debug: Add WriteLn statements to check values
• Experiment: Modify examples to understand concepts

Running Pascal Programs in Time Warp Studio

1. Create a .pas file with your program
2. Select "Pascal" from the language dropdown
3. Paste your code or load the file
4. Click Run or press Ctrl+R
5. Interact with the program in the Output panel

Next Steps

• Learn C for systems programming
• Explore Python for general programming
• Try BASIC for classic programming
• Learn Logo for turtle graphics

Happy Pascal programming!