strfmon - convert monetary value to string
ssize_t strfmon(char *s, size_t maxsize, const char *format,
The strfmon() function places characters into the array
pointed to by s as controlled by the string pointed to by
format. No more than maxsize bytes are placed into the
The format is a character string that contains two types of
objects: plain characters, which are simply copied to the
output stream, and conversion specifications, each of which
results in the fetching of zero or more arguments which are
converted and formatted. The results are undefined if there
are insufficient arguments for the format. If the format is
exhausted while arguments remain, the excess arguments are
A conversion specification consists of the following
o a % character
o optional flags
o optional field width
o optional left precision
o optional right precision
o a required conversion character that determines the
conversion to be performed.
One or more of the following optional flags can be specified
to control the conversion:
=f An = followed by a single character f which is used as
the numeric fill character. The fill character must be
representable in a single byte in order to work with
precision and width counts. The default numeric fill
character is the space character. This flag does not
affect field width filling which always uses the space
character. This flag is ignored unless a left preci-
sion (see below) is specified.
^ Do not format the currency amount with grouping char-
acters. The default is to insert the grouping charac-
ters if defined for the current locale.
+ or (
Specify the style of representing positive and nega-
tive currency amounts. Only one of `+' or `(' may be
specified. If `+' is specified, the locale's
equivalent of + and `-' are used (for example, in the
U.S.A.: the empty string if positive and `-' if nega-
tive). If `(' is specified, negative amounts are
enclosed within parentheses. If neither flag is speci-
fied, the `+' style is used.
! Suppress the currency symbol from the output conver-
- Specify the alignment. If this flag is present all
fields are left-justified (padded to the right)
rather than right-justified.
w A decimal digit string w specifying a minimum field
width in bytes in which the result of the conversion
is right-justified (or left-justified if the flag `-'
is specified). The default is zero.
#n A `#' followed by a decimal digit string n specifying
a maximum number of digits expected to be formatted to
the left of the radix character. This option can be
used to keep the formatted output from multiple calls
to the strfmon() aligned in the same columns. It can
also be used to fill unused positions with a special
character as in $***123.45. This option causes an
amount to be formatted as if it has the number of
digits specified by n. If more than n digit positions
are required, this conversion specification is
ignored. Digit positions in excess of those actually
required are filled with the numeric fill character
(see the =f flag above).
If grouping has not been suppressed with the `^' flag,
and it is defined for the current locale, grouping
separators are inserted before the fill characters (if
any) are added. Grouping separators are not applied to
fill characters even if the fill character is a digit.
To ensure alignment, any characters appearing before
or after the number in the formatted output such as
currency or sign symbols are padded as necessary with
space characters to make their positive and negative
formats an equal length.
.p A period followed by a decimal digit string p specify-
ing the number of digits after the radix character. If
the value of the right precision p is zero, no radix
character appears. If a right precision is not
included, a default specified by the current locale is
used. The amount being formatted is rounded to the
specified number of digits prior to formatting.
The conversion characters and their meanings are:
i The double argument is formatted according to the
locale's international currency format (for example,
in the U.S.A.: USD 1,234.56).
n The double argument is formatted according to the
locale's national currency format (for example, in the
% Convert to a %; no argument is converted. The entire
conversion specification must be %%.
The LC_MONETARY category of the program's locale affects the
behavior of this function including the monetary radix char-
acter (which may be different from the numeric radix charac-
ter affected by the LC_NUMERIC category), the grouping
separator, the currency symbols and formats. The interna-
tional currency symbol should be in conformance with the ISO
4217: 1987 standard.
If the total number of resulting bytes (including the ter-
minating null byte) is not more than maxsize, strfmon()
returns the number of bytes placed into the array pointed to
by s, not including the terminating null byte. Otherwise, -1
is returned, the contents of the array are indeterminate,
and errno is set to indicate the error.
The strfmon() function will fail if:
The function is not supported.
E2BIG Conversion stopped due to lack of space in the buffer.
Example 1: A sample output of strfmon().
Given a locale for the U.S.A. and the values 123.45,
-123.45, and 3456.781:
| Conversion Output Comments |
| Specification |
| %n $123.45 default formatting |
| -$123.45 |
| $3,456.78 |
| %11n $123.45 right align within an 11 |
| -$123.45 character field |
| $3,456.78 |
| %#5n $123.45 aligned columns for values |
| -$123.45 up to 99,999 |
| $3,456.78 |
| %=*#5n $***123.45 specify a fill character |
| -$***123.45 |
| $*3,456.78 |
| %=0#5n $000123.45 fill characters do not use |
| -$000123.45 grouping even if the fill |
| $03,456.78 character is a digit |
| %^#5n $123.45 disable the grouping |
| -$123.45 separator |
| $3456.78 |
| %^#5.0n $123 round off to whole units |
| -$123 |
| $3457 |
| %^#5.4n $123.4500 increase the precision |
| -$123.4500 |
| $3456.7810 |
| %(#5n 123.45 use an alternative |
| ($123.45) pos/neg style |
| $3,456.78 |
| %!(#5n 123.45 disable the currency |
| (123.45) symbol |
| 3,456.78 |
See attributes(5) for descriptions of the following attri-
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
| MT-Level | MT-Safe with exceptions |
| CSI | Enabled |
localeconv(3C), setlocale(3C), attributes(5)
This function can be used safely in multithreaded applica-
tions, as long as setlocale(3C) is not called to change the
Man(1) output converted with