Pascal Programming Cheatsheet

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Programming Languages / Pascal

March 03, 2025 00:30

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Fundamentals

Program Structure

A Pascal program generally follows this structure:

program ProgramName;

uses
  {Units}; // e.g., crt, sysutils

const
  {Constants}; // e.g., MaxValue = 100;

type
  {Type Definitions}; // e.g., String20 = string[20];

var
  {Variable Declarations}; // e.g., counter : integer;

procedure ProcedureName;
begin
  {Procedure Body}
end;

function FunctionName : ReturnType;
begin
  {Function Body}
  FunctionName := ReturnValue;
end;

begin
  {Main Program Body}
end.

Data Types

Integer Types	integer, shortint, longint, byte, word```
Real Types	real, single, double, extended```
Character Type	char```
Boolean Type	boolean```
String Type	string[max_length] // or simply string```

Variable Declaration

Variables must be declared before use.

var
  variableName: DataType;
  anotherVariable: DataType;

Example:

var
  age: integer;
  name: string[50];

Control Structures

Conditional Statements

If-Then-Else

if condition then
begin
  {Statements}
end
else
begin
  {Statements}
end;

Case Statement

case variable of
  value1: begin
    {Statements}
  end;
  value2: begin
    {Statements}
  end;
  else
  begin
    {Statements}
  end;
end;

Looping Structures

For Loop

for i := startValue to endValue do
begin
  {Statements}
end;

While Loop

while condition do
begin
  {Statements}
end;

Repeat-Until Loop

repeat
  {Statements}
until condition;

Procedures and Functions

Procedure Definition

procedure ProcedureName(parameter1: DataType; parameter2: DataType);
var
  {Local Variables};
begin
  {Procedure Body}
end;

Function Definition

function FunctionName(parameter1: DataType; parameter2: DataType): ReturnType;
var
  {Local Variables};
begin
  {Function Body}
  FunctionName := ReturnValue;
end;

Parameters

Value Parameters	The value of the actual parameter is copied to the formal parameter.
Variable (Var) Parameters	The formal parameter becomes a reference to the actual parameter. Changes to the formal parameter affect the actual parameter.

Input/Output and Standard Functions

Input/Output

Reading Input

read(variable1, variable2, ...);
readln(variable1, variable2, ...); // Reads a line

Writing Output

write(expression1, expression2, ...);
writeln(expression1, expression2, ...); // Writes a line

Standard Functions

`abs(x)`	Returns the absolute value of x.
`sqr(x)`	Returns the square of x.
`sqrt(x)`	Returns the square root of x.
`sin(x), cos(x)`	Returns the sine and cosine of x (in radians).
`arctan(x)`	Returns the arctangent of x.
`exp(x)`	Returns e raised to the power of x.
`ln(x)`	Returns the natural logarithm of x.
`round(x)`	Rounds x to the nearest integer.
`trunc(x)`	Truncates x to the integer part.