Basic Syntax & Data Types

Understanding the basic syntax rules of Pascal is crucial, as the compiler is very strict. Pascal is a strongly typed language, meaning every variable must be declared with a specific data type, and that type cannot change.

1. Pascal Syntax Rules

2. Variable Declaration

In Pascal, all variables must be declared in a dedicated var section before the begin of the program or procedure.

program Declarations;

var
  // Syntax: VariableName : DataType;
  UserAge   : Integer;
  UserName  : String;
  IsActive  : Boolean;

begin
  // ... code goes here ...
end.

3. Fundamental Data Types

Pascal has distinct categories for storing whole numbers, decimals, characters, and logical values.

A. Ordinal Types (Whole Numbers)

Ordinal types have a definite, ordered set of values (e.g., you can say what the “next” value is).

B. Real Types (Decimal Numbers)

Real types store fractional numbers. They do not have defined successors or predecessors, so they are not ordinal types.

C. Other Simple Types

4. Assignments and Operations

You assign values to variables and perform calculations using operators.

A. Example Assignment

var
  A, B: Integer;
  Sum: Integer;
  IsHigh: Boolean;

begin
  A := 10;        // Assigns 10 to A
  B := 5;         // Assigns 5 to B
  Sum := A + B;   // Arithmetic: Sum is 15
  IsHigh := (A > 15); // Comparison: IsHigh is False
end.

B. Arithmetic Operators

var
  Total: Real;
  Quotient: Integer;

begin
  Total := 10 / 3;    // Total is 3.333... (Real division)
  Quotient := 10 div 3; // Quotient is 3 (Integer division)
end.