Variables and constants in Delphi

A bakery till works out a morning's takings from a fixed loaf price.

program VariablesConst;
uses SysUtils;

const
  ShopName = 'Rye and Reason';
  LoafPrice = 4.25;
var
  LoavesSold: Integer;
  Takings: Double;
  DoorOpen: Boolean;
begin
  // := assigns to a variable; = only names a constant or compares.
  LoavesSold := 38;
  Takings := LoavesSold * LoafPrice;
  DoorOpen := False;
  WriteLn(ShopName);
  WriteLn(Format('%d loaves sold, %.2f taken', [LoavesSold, Takings]));
  WriteLn('door open: ', DoorOpen);
end.

How it works

1. The const block names ShopName and LoafPrice, neither of which can change.
2. The var block declares an Integer, a Double and a Boolean in one place.
3. Takings := LoavesSold * LoafPrice; assigns with :=, never with =.

Keywords and builtins used here

• Boolean
• Double
• False
• Format
• Integer
• WriteLn
• begin
• const
• end
• program
• uses
• var

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Step 2 of 3 in Programs & variables, step 2 of 27 in Language basics.

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