CurrencyTests.dpr

program CurrencyTests;

{$APPTYPE CONSOLE}

{$R *.res}


uses
  System.SysUtils;

begin
  try
    // Type Currency is an Integer internally and its ToString routines are optimized for money values
    // https://docwiki.embarcadero.com/Libraries/Sydney/en/System.Currency

    // Currency has a max precision of 4, if you pass in a value with 5 decimals, then an implicit conversion from
    // float to currency is performed, which includes a round operation
    var
      b: Currency := 3.6199;

    Assert(b * 10000 = 36199); // Integer comparison
    Assert(Trunc(b) = 3); // Integer comparison

    b := 3.61999; // Right side is a float constant (!!!)

    Assert(b * 10000 = 36200); // Integer comparison
    Assert(Trunc(b) = 3); // Integer comparison

    //String tests
    b := 3.6199;
    // ToString is determined by Format settings
    // FormatSettings are locale dependent - we want a testable setup here
    // https://docwiki.embarcadero.com/Libraries/Sydney/en/System.SysUtils.TFormatSettings.CurrencyDecimals
    FormatSettings.CurrencyDecimals := 4; // Default is 2 - max is 4

    // https://docwiki.embarcadero.com/Libraries/Sydney/en/System.SysUtils.TFormatSettings.CurrencyFormat
    FormatSettings.CurrencyFormat := 0; // $123

    // https://docwiki.embarcadero.com/Libraries/Sydney/en/System.SysUtils.TFormatSettings.CurrencyString
    FormatSettings.CurrencyString := '$';

    FormatSettings.DecimalSeparator := '.';

    var
    s := b.ToString;
    Assert(s = '$3.6199');
  except
    on E: Exception do
      writeln(E.ClassName, ': ', E.Message);
  end;

end.