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# Pascal Cheatsheet

Pascal is a procedural programming language that was designed to encourage good programming practices and readability. It is widely used in education and scientific computing for tasks such as numerical analysis, data processing, and simulation.

## Unique Features

- Strong typing
- Structured programming constructs
- Modular programming
- Pointers and dynamic memory allocation
- Object-oriented programming (in some dialects)

## Variables

Variables in Pascal are declared using the `var` keyword. Pascal supports static typing, so you need to specify the type of the variable.

var

name: string;

age: integer;

pi: double;

## Functions

Functions in Pascal are declared using the `function` keyword followed by the function name and parameters. Pascal supports nested functions, which are functions that are defined inside other functions.

function greet(name: string): string;

begin

greet := 'Hello, ' + name + '!';

end;

writeln(greet('John'));

var

add: function(a, b: integer): integer;

add := function(a, b: integer): integer

begin

add := a + b;

end;

writeln(add(2, 3));

## Loops

Pascal supports `for`, `while`, and `repeat until` loops, as well as the `if`, `else if`, and `else` statements.

var

numbers: array[1..5] of integer;

i: integer;

numbers := (1, 2, 3, 4, 5);

for i := 1 to 5 do

writeln(numbers[i]);

i := 0;

while i < 5 do

begin

writeln(i);

i := i + 1;

end;

i := 0;

repeat

writeln(i);

i := i + 1;

until i >= 5;

## Conditionals

Pascal supports `if`, `else if`, and `else` statements, as well as the ternary operator (in some dialects).

var

age: integer;

result: string;

age := 30;

if age < 18 then

writeln('You are too young to vote.')

else if age < 21 then

writeln('You can vote, but not drink.')

else

writeln('You can vote and drink.');

if age >= 18 then

result := 'You are an adult'

else

result := 'You are not an adult';

writeln(result);

## File Manipulation

Pascal provides several ways to read and write files. You can use the `Assign`, `Rewrite`, `Reset`, `Write`, `Read`, and `Close` functions to create, read, write, and delete files.

var

fileHandle: text;

content: string;

Assign(fileHandle, 'example.txt');

Rewrite(fileHandle);

Write(fileHandle, 'Hello, world!');

Close(fileHandle);

Reset(fileHandle);

Read(fileHandle, content);

Close(fileHandle);

writeln(content);

Erase(fileHandle);

## Resources

- [Free Pascal Documentation](https://www.freepascal.org/docs.html)
- [Pascal Style Guide](https://www.cs.cornell.edu/courses/cs312/2002sp/styleguide/pascal.html)
- [Pascal Tutorials](https://www.tutorialspoint.com/pascal/index.htm)
- [Pascal Programming for Schools](http://pascal-programming.info/)
- [Pascal Compiler Online](https://www.onlinegdb.com/online_pascal_compiler)