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| Standard C Library Functions | strfmon(3C) |
| | strfmon - convert monetary value to string |
SYNOPSIS
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#include <monetary.h> ssize_t strfmon(char *s, size_t maxsize, const char *format, ...); |
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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 array.
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 simply ignored.
A conversion specification consists of the following sequence:
- a % character
- optional flags
- optional field width
- optional left precision
- optional right precision
- a required conversion character that determines the conversion to be performed.
Flags
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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 precision (see below) is specified.
- ^
- Do not format the currency amount with grouping characters. The default is to insert the grouping characters if defined for the current locale.
- + or (
- Specify the style of representing positive and negative 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 negative). If `(' is specified, negative amounts are enclosed within parentheses. If neither flag is
specified, the `+' style is used.
- !
- Suppress the currency symbol from the output conversion.
- -
- Specify the alignment. If this flag is present all fields are left-justified (padded to the right) rather than right-justified.
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Field Width
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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.
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Left Precision
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- #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.
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Right Precision
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- .p
- A period followed by a decimal digit string p specifying 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.
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Conversion Characters
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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 U.S.A.: $1,234.56).
- %
- Convert to a %; no argument is converted. The entire conversion specification must be %%.
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Locale Information
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The LC_MONETARY category of the program's locale affects the behavior of this function including the monetary radix character (which may be different from the numeric radix character
affected by the LC_NUMERIC category), the grouping separator, the currency symbols and formats. The international currency symbol should be in conformance with the ISO 4217: 1987 standard.
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If the total number of resulting bytes (including the terminating 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.
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The strfmon() function will fail if:
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ENOSYS
- The function is not supported.
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E2BIG
- Conversion stopped due to lack of space in the buffer.
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| | Example 1. A sample output of strfmon.
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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 | |
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See attributes(5) for descriptions of the following
attributes:
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
| MT-Level | MT-Safe with exceptions |
| CSI | Enabled |
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This function can be used safely in multithreaded applications, as long as setlocale(3C)
is not called to change the locale.
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