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System.AnsiStrings.Format

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Delphi

function Format(const Format: AnsiString; const Args: array of const): AnsiString;
function Format(const Format: AnsiString; const Args: array of const; const AFormatSettings: TFormatSettings): AnsiString;

C++

extern DELPHI_PACKAGE System::AnsiString __fastcall Format(const System::AnsiString Format, const System::TVarRec *Args, const int Args_High)/* overload */;

Properties

Type Visibility Source Unit Parent
function public
System.AnsiStrings.pas
System.AnsiStrings.hpp
System.AnsiStrings System.AnsiStrings

Description

Formats the argument list given by the Args parameter using the format string given by the Format parameter.

Format strings contain two types of objects: plain characters and format specifiers. Plain characters are copied verbatim to the resulting string. Format specifiers fetch arguments from the argument list and apply formatting to them.

Format specifiers have the following form:

% ["index" :] [-] ["width"] [. "prec"] "type"

A format specifier begins with a % character. After the % come the following, in this order:

  1. An optional argument index specifier, ["index" :]
  2. An optional left-justification indicator, [-]
  3. An optional width specifier, ["width"]
  4. An optional precision specifier, [. "prec"]
  5. The required conversion type character, "type"

Conversion Characters

The following conversion characters are supported:

Value Meaning

d

Decimal. The argument must be an integer value. The value is converted to a string of decimal digits. The resulting string starts with a minus sign if the number is negative. If the format string contains a precision specifier, it indicates that the resulting string must contain at least the specified number of digits; if the value has less digits, the resulting string is left-padded with zeros.

u

Unsigned decimal. Similar to d, but no sign is output.

e

Scientific. The argument must be a floating-point value. The value is converted to a string of the form "-d.ddd...E+ddd". The resulting string starts with a minus sign if the number is negative, and one digit always precedes the decimal point. The total number of digits in the resulting string (including the one before the decimal point) is given by the precision specifier in the format string; a default precision of 15 is assumed if no precision specifier is present. The "E" exponent character in the resulting string is always followed by a plus or minus sign and at least three digits.

f

Fixed. The argument must be a floating-point value. The value is converted to a string of the form "-ddd.ddd...". The resulting string starts with a minus sign if the number is negative. The number of digits after the decimal point is given by the precision specifier in the format string; a default of 2 decimal digits is assumed if no precision specifier is present.

g

General. The argument must be a floating-point value. The value is converted to the shortest possible decimal string using fixed or scientific format. The number of significant digits in the resulting string is given by the precision specifier in the format string; a default precision of 15 is assumed if no precision specifier is present. Trailing zeros are removed from the resulting string, and a decimal point appears only if necessary. The resulting string uses fixed-point format if the number of digits to the left of the decimal point in the value is less than or equal to the specified precision and if the value is greater than or equal to 0.00001. Otherwise, the resulting string uses scientific format.

n

Number. The argument must be a floating-point value. The value is converted to a string of the form "-d,ddd,ddd.ddd...". The n format corresponds to the f format, except that the resulting string contains thousand separators.

m

Money. The argument must be a floating-point value. The value is converted to a string that represents a currency amount. The conversion is controlled by the CurrencyString, CurrencyFormat, NegCurrFormat, ThousandSeparator, DecimalSeparator, and CurrencyDecimals global variables, all of which are initialized from locale settings provided by the operating system. For example, currency format preferences can be set in the International section of the Windows Control Panel. If the format string contains a precision specifier, it overrides the value given by the CurrencyDecimals global variable.

p

Pointer. The argument must be a pointer value. The value is converted to a string of the form "XXXX:YYYY", where XXXX and YYYY are the segment and offset parts of the pointer expressed as four hexadecimal digits.

s

String. The argument must be a character, a string, or a PChar value. The string or character is inserted in place of the format specifier. The precision specifier, if present in the format string, specifies the maximum length of the resulting string. If the argument is a string that is longer than this maximum, the string is truncated.

x

Hexadecimal. The argument must be an integer value. The value is converted to a string of hexadecimal digits. If the format string contains a precision specifier, it indicates that the resulting string must contain at least the specified number of digits. If the value has less digits, the resulting string is left-padded with zeros.

Conversion characters may be specified in uppercase as well as in lowercase; both produce the same results.

For all floating-point formats, the actual characters used as decimal and thousand separators are obtained from the DecimalSeparator and ThousandSeparator global variables.

Index, width, and precision specifiers can be specified directly using a decimal digit string (for example "%10d"), or indirectly, using an asterisk character (for example "%*.*f"). When using an asterisk, the next argument in the argument list (which must be an integer value) becomes the value that is actually used. For example, these two are equivalent:

Format('%*.*f', [8, 2, 123.456])
Format('%8.2f', [123.456])

A width specifier sets the minimum field width for a conversion. If the resulting string is shorter than the minimum field width, the string is padded with blanks to increase the field width. The default is to right-justify the result by adding blanks in front of the value, but if the format specifier contains a left-justification indicator (a "-" character preceding the width specifier), the result is left-justified by adding blanks after the value.

An index specifier sets the current argument list index to the specified value. The index of the first argument in the argument list is 0. Using index specifiers, it is possible to format the same argument multiple times. For example:

Format('%d %d %0:d %d', [10, 20])

produces the string:

'10 20 10 20'

The Format function can be combined with other formatting functions. For example:

S := Format('Your total was %s on %s', [FormatFloat('$#,##0.00;;zero', Total), FormatDateTime('mm/dd/yy', Date)]);

This code uses the FormatFloat and FormatDateTime functions to customize the format beyond what is possible with the Format function.

Each of the string formatting routines that uses global variables for formatting (separators, decimals, date/time formats, and so forth) has an overloaded equivalent requiring a parameter of type TFormatSettings. This additional parameter provides the formatting information rather than the global variables. For more information, see the documentation for TFormatSettings.

See Also

Code Examples


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