The Basic Types

Pascal has four basic types you'll use constantly: integer (whole numbers), real (decimals), string (text), and boolean (true/false).

var
  age: integer;
  gpa: real;
  name: string;
  passed: boolean;
begin
  age := 20;
  gpa := 4.5;
  name := 'Ada';
  passed := true;
end.

Arithmetic operators

writeln(7 + 3);   { 10 }
writeln(7 - 3);   { 4 }
writeln(7 * 3);   { 21 }
writeln(7 / 3);   { always a real, even for whole numbers }
writeln(7 div 3); { 2 -- div is integer division }
writeln(7 mod 3); { 1 -- mod is the remainder }

Comparison and logical operators

writeln(5 = 5);               { TRUE }
writeln(5 <> 3);              { TRUE }
writeln((5 > 3) and (2 < 4)); { TRUE }
writeln((5 > 3) or (2 > 4));  { TRUE }
writeln(not true);            { FALSE }

Why This Matters for Your Exams

/ vs div is the single most common source of "wrong type" bugs -- / always produces a real, even for two whole numbers, while div truncates to an integer. Mixing them up where an integer is required fails to compile.

Try it yourself