Delphi Basics : FloatToStrF command

DelphiBasics

FloatToStrF
Function

Convert a floating point value to a string with formatting

SysUtils unit

1	function FloatToStrF(Value Extended; Format TFloatFormat; Precision, Digits Integer):string;
2	function FloatToStrF (Value Extended; Format TFloatFormat; Precision, Digits Integer; const?FormatSettings TFormatSettings:string;

Description

The FloatToStrF function converts a floating point number Value into a displayable string, with great control over the formatting via the Format, Precision, and Digits values.

The Value type may be any of the floating point types.

The Format parameter is defined by the TFloatFormat (SysUtils) type :

ffCurrency	eg : ?2,345.60
ffExponent	eg : 2.3456E+04
ffFixed	eg : 2345.60
ffGeneral	eg : 2345.6
ffNumber	eg : 2,345.6

The other parameters are dependent on this format. See TFloatFormat for full details.

Version 2 of this function is for use within threads. You furnish the FormatSettings record before invoking the call. It takes a local copy of global formatting variables that make the routine thread safe.

Notes

You can change the currency string from the default (such as '$' in the USA, '?' in the UK) using the CurrencyString variable.

You can change the position of the currency string using the CurrencyFormat variable.

You can change the decimal point value by setting the DecimalSeparator character.

You can change the thousands separator value by setting the ThousandSeparator character.

If the full number of digits before the decimal point (the mantissa) cannot be displayed, then the display reverts to the exponent (scientific) format.

Related commands

CurrencyDecimals		Defines decimal digit count in the Format function
CurrencyFormat		Defines currency string placement in curr display functions
CurrencyString		The currency string used in currency display functions
DecimalSeparator		The character used to display the decimal point
FloatToStr		Convert a floating point value to a string
NegCurrFormat		Defines negative amount formatting in currency displays
TFloatFormat		Formats for use in floating point number display functions
ThousandSeparator		The character used to display the thousands separator

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Example code : Display numbers as financial values

var
  amount1 : Extended;
begin
  amount1 := 1234.567;

  // Display in a Currency format
  CurrencyString := '? ';
  ShowMessage('Using 8,4 = '+FloatToStrF(amount1, ffCurrency, 8, 4));
  ShowMessage('Using 4,4 = '+FloatToStrF(amount1, ffCurrency, 4, 4));
  ShowMessage('Using 4,2 = '+FloatToStrF(amount1, ffCurrency, 4, 2));
  ShowMessage('Using 2,4 = '+FloatToStrF(amount1, ffCurrency, 2, 4));
end;

Show full unit code

  Using 8,4 = ? 1,234.5670
  Using 4,4 = ? 1,235.0000
  Using 4,2 = ? 1,235.00
  Using 2,4 = 1.2E0003

Example code : Display numbers with Scientific formatting

var
  amount1 : Extended;
begin
  amount1 := 1234.567;

  // Display in a Scientific format
  ShowMessage('Using 8,4 = '+FloatToStrF(amount1, ffExponent, 8, 4));
  ShowMessage('Using 4,4 = '+FloatToStrF(amount1, ffExponent, 4, 4));
  ShowMessage('Using 4,2 = '+FloatToStrF(amount1, ffExponent, 4, 2));
  ShowMessage('Using 2,4 = '+FloatToStrF(amount1, ffExponent, 2, 4));
end;

Show full unit code

  Using 8,4 = 1.2345670E+0003
  Using 4,4 = 1.235E+0003
  Using 4,2 = 1.235E+03
  Using 2,4 = 1.2E+0003

Example code : General display of numbers

var
  amount1 : Extended;
begin
  amount1 := 1234.567;

  // Display in Fixed format
  ShowMessage('Fixed formatting :');
  ShowMessage('');
  ShowMessage('Using 8,4 = '+FloatToStrF(amount1, ffFixed, 8, 4));
  ShowMessage('Using 4,4 = '+FloatToStrF(amount1, ffFixed, 4, 4));
  ShowMessage('Using 4,2 = '+FloatToStrF(amount1, ffFixed, 4, 2));
  ShowMessage('Using 2,4 = '+FloatToStrF(amount1, ffFixed, 2, 4));

  // Display in General format
  ShowMessage('');
  ShowMessage('General formatting :');
  ShowMessage('');
  ShowMessage('Using 8,4 = '+FloatToStrF(amount1, ffGeneral, 8, 4));
  ShowMessage('Using 4,4 = '+FloatToStrF(amount1, ffgeneral, 4, 4));
  ShowMessage('Using 4,2 = '+FloatToStrF(amount1, ffGeneral, 4, 2));
  ShowMessage('Using 2,4 = '+FloatToStrF(amount1, ffGeneral, 2, 4));

  // Display in Number format
  ShowMessage('');
  ShowMessage('Number formatting :');
  ShowMessage('');
  ShowMessage('Using 8,4 = '+FloatToStrF(amount1, ffNumber, 8, 4));
  ShowMessage('Using 4,4 = '+FloatToStrF(amount1, ffNumber, 4, 4));
  ShowMessage('Using 4,2 = '+FloatToStrF(amount1, ffNumber, 4, 2));
  ShowMessage('Using 2,4 = '+FloatToStrF(amount1, ffNumber, 2, 4));
end;

Show full unit code

  Fixed formatting :

  Using 8,4 = 1234.5670
  Using 4,4 = 1235.0000
  Using 4,2 = 1235.00
  Using 2,4 = 1.2E0003

  General formatting :

  Using 8,4 = 1234.567
  Using 4,4 = 1235
  Using 4,2 = 1235
  Using 2,4 = 1.2E0003

  Number formatting :

  Using 8,4 = 1,234.5670
  Using 4,4 = 1,235.0000
  Using 4,2 = 1,235.00
  Using 2,4 = 1.2E0003