# fmt_xlonglong man page

fmt_xlonglong — write a hexadecimal ASCII representation of an unsigned long long integer

## Syntax

**#include <fmt.h>**

size_t **fmt_xlonglong**(char **dest*,unsigned long long *source*);

## Description

fmt_xlonglong writes an ASCII representation ('0' to '9' and 'a' to 'f', base 16) of *source* to *dest* and returns the number of bytes written.

fmt_xlonglong does not append \0.

If *dest* equals FMT_LEN (i.e. is zero), fmt_xlonglong returns the number of bytes it would have written.

For convenience, fmt.h defines the integer FMT_XLONG to be big enough to contain every possible fmt_xlonglong output plus \0.