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(gmp.info)Formatted Output Functions

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Functions
=========

   Each of the following functions is similar to the corresponding C
library function.  The basic `printf' forms take a variable argument
list.  The `vprintf' forms take an argument pointer, see Note: Variadic
Functions, or `man 3 va_start'.

   It should be emphasised that if a format string is invalid, or the
arguments don't match what the format specifies, then the behaviour of
any of these functions will be unpredictable.  GCC format string
checking is not available, since it doesn't recognise the GMP
extensions.

   The file based functions `gmp_printf' and `gmp_fprintf' will return
-1 to indicate a write error.  All the functions can return -1 if the C
library `printf' variant in use returns -1, but this shouldn't normally
occur.

 - Function: int gmp_printf (const char *FMT, ...)
 - Function: int gmp_vprintf (const char *FMT, va_list AP)
     Print to the standard output `stdout'.  Return the number of
     characters written, or -1 if an error occurred.

 - Function: int gmp_fprintf (FILE *FP, const char *FMT, ...)
 - Function: int gmp_vfprintf (FILE *FP, const char *FMT, va_list AP)
     Print to the stream FP.  Return the number of characters written,
     or -1 if an error occurred.

 - Function: int gmp_sprintf (char *BUF, const char *FMT, ...)
 - Function: int gmp_vsprintf (char *BUF, const char *FMT, va_list AP)
     Form a null-terminated string in BUF.  Return the number of
     characters written, excluding the terminating null.

     No overlap is permitted between the space at BUF and the string
     FMT.

     These functions are not recommended, since there's no protection
     against exceeding the space available at BUF.

 - Function: int gmp_snprintf (char *BUF, size_t SIZE, const char *FMT,
          ...)
 - Function: int gmp_vsnprintf (char *BUF, size_t SIZE, const char
          *FMT, va_list AP)
     Form a null-terminated string in BUF.  No more than SIZE bytes
     will be written.  To get the full output, SIZE must be enough for
     the string and null-terminator.

     The return value is the total number of characters which ought to
     have been produced, excluding the terminating null.  If RETVAL >=
     SIZE then the actual output has been truncated to the first SIZE-1
     characters, and a null appended.

     No overlap is permitted between the region {BUF,SIZE} and the FMT
     string.

     Notice the return value is in ISO C99 `snprintf' style.  This is
     so even if the C library `vsnprintf' is the older GLIBC 2.0.x
     style.

 - Function: int gmp_asprintf (char **PP, const char *FMT, ...)
 - Function: int gmp_vasprintf (char *PP, const char *FMT, va_list AP)
     Form a null-terminated string in a block of memory obtained from
     the current memory allocation function (Note: Custom
     Allocation).  The block will be the size of the string and
     null-terminator.  Put the address of the block in *PP.  Return the
     number of characters produced, excluding the null-terminator.

     Unlike the C library `asprintf', `gmp_asprintf' doesn't return -1
     if there's no more memory available, it lets the current allocation
     function handle that.

 - Function: int gmp_obstack_printf (struct obstack *OB, const char
          *FMT, ...)
 - Function: int gmp_obstack_vprintf (struct obstack *OB, const char
          *FMT, va_list AP)
     Append to the current obstack object, in the same style as
     `obstack_printf'.  Return the number of characters written.  A
     null-terminator is not written.

     FMT cannot be within the current obstack object, since the object
     might move as it grows.

     These functions are available only when the C library provides the
     obstack feature, which probably means only on GNU systems, see
     Note: Obstacks.