---
name: "strfmon"
section: "3"
platform: "macos"
package: "Libc"
version: "1752.120.2"
release: "macOS 26.5"
platforms: ["linux", "freebsd", "macos"]
url: "https://new.carta.tech/strfmon"
---

# strfmon(3)

convert monetary value to string

## NAME

**strfmon**, **strfmon\_l** – convert monetary value to string

## SYNOPSIS

**#include \<monetary.h\>**

*ssize\_t*\

**strfmon**(*char \*restrict s*, *size\_t maxsize*, *const char \*restrict format*, *...*);

**#include \<monetary.h\>**

**#include \<xlocale.h\>**

*ssize\_t*\

**strfmon\_l**(*char \*restrict s*, *size\_t maxsize*, *locale\_t loc*, *const char \*restrict format*, *...*);

## DESCRIPTION

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.

While the **strfmon**() function uses the current locale, the **strfmon\_l**() function may be passed a locale directly. See [xlocale(3)](/xlocale/3.md) for more information.

The format string is composed of zero or more directives: ordinary characters (not **%**), which are copied unchanged to the output stream; and conversion specifications, each of which results in fetching zero or more subsequent arguments. Each conversion specification is introduced by the **%** character. After the **%**, the following appear in sequence:

- Zero or more of the following flags:

  - **=***f*

    A ‘**=**’ character followed by another character *f* which is used as the numeric fill character.

  - **^**

    Do not use grouping characters, regardless of the current locale default.

  - **+**

    Represent positive values by prefixing them with a positive sign, and negative values by prefixing them with a negative sign. This is the default.

  - **(**

    Enclose negative values in parentheses.

  - **!**

    Do not include a currency symbol in the output.

  - **-**

    Left justify the result. Only valid when a field width is specified.

- An optional minimum field width as a decimal number. By default, there is no minimum width.

- A ‘**#**’ sign followed by a decimal number specifying the maximum expected number of digits after the radix character.

- A ‘**.**’ character followed by a decimal number specifying the number of digits after the radix character.

- One of the following conversion specifiers:

  - **i**

    The *double* argument is formatted as an international monetary amount.

  - **n**

    The *double* argument is formatted as a national monetary amount.

  - **%**

    A ‘%’ character is written.

## RETURN VALUES

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.

## ERRORS

The **strfmon**() function will fail if:

- \[E2BIG\]

  Conversion stopped due to lack of space in the buffer.

- \[EINVAL\]

  The format string is invalid.

- \[ENOMEM\]

  Not enough memory for temporary buffers.

## EXAMPLE

```
  #include <stdio.h>
  #include <monetary.h>
  #include <locale.h>
  int main() {
          char buf[200];
          setlocale(LC_ALL, "en_US");
          (void)strfmon (buf, sizeof(buf)-1, "%n" , 123456.78);
          printf("%s0, buf);
  }
```

## SEE ALSO

[localeconv(3)](/localeconv/3.md), [xlocale(3)](/xlocale/3.md)

## STANDARDS

The **strfmon**() function conforms to IEEE Std 1003.1-2001 (“POSIX.1”).

## AUTHORS

The **strfmon**() function was implemented by Alexey Zelkin ⟨phantom@FreeBSD.org⟩.

This manual page was written by Jeroen Ruigrok van der Werven ⟨asmodai@FreeBSD.org⟩ based on the standard's text.

## BUGS

The **strfmon**() function does not correctly handle multibyte characters in the *format* argument.