4.1 Headers and Libraries

All declarations needed to use MPFR are collected in the include file mpfr.h. It is designed to work with both C and C++ compilers. You should include that file in any program using the MPFR library:

#include <mpfr.h>

Note, however, that prototypes for MPFR functions with FILE * parameters are provided only if <stdio.h> is included too (before mpfr.h):

#include <stdio.h>
#include <mpfr.h>

Likewise <stdarg.h> (or <varargs.h>) is required for prototypes with va_list parameters, such as mpfr_vprintf.

And for any functions using intmax_t, you must include <stdint.h> or <inttypes.h> before mpfr.h, to allow mpfr.h to define prototypes for these functions. Moreover, under some platforms (in particular with C++ compilers), users may need to define MPFR_USE_INTMAX_T (and should do it for portability) before mpfr.h has been included; of course, it is possible to do that on the command line, e.g., with -DMPFR_USE_INTMAX_T.

Note: If mpfr.h and/or gmp.h (used by mpfr.h) are included several times (possibly from another header file), <stdio.h> and/or <stdarg.h> (or <varargs.h>) should be included before the first inclusion of mpfr.h or gmp.h. Alternatively, you can define MPFR_USE_FILE (for MPFR I/O functions) and/or MPFR_USE_VA_LIST (for MPFR functions with va_list parameters) anywhere before the last inclusion of mpfr.h. As a consequence, if your file is a public header that includes mpfr.h, you need to use the latter method.

When calling a MPFR macro, it is not allowed to have previously defined a macro with the same name as some keywords (currently do, while and sizeof).

You can avoid the use of MPFR macros encapsulating functions by defining the MPFR_USE_NO_MACRO macro before mpfr.h is included. In general this should not be necessary, but this can be useful when debugging user code: with some macros, the compiler may emit spurious warnings with some warning options, and macros can prevent some prototype checking.

All programs using MPFR must link against both libmpfr and libgmp libraries. On a typical Unix-like system this can be done with ‘-lmpfr -lgmp’ (in that order), for example:

gcc myprogram.c -lmpfr -lgmp

MPFR is built using Libtool and an application can use that to link if desired, see GNU Libtool.

If MPFR has been installed to a non-standard location, then it may be necessary to set up environment variables such as ‘C_INCLUDE_PATH’ and ‘LIBRARY_PATH’, or use ‘-I’ and ‘-L’ compiler options, in order to point to the right directories. For a shared library, it may also be necessary to set up some sort of run-time library path (e.g., ‘LD_LIBRARY_PATH’) on some systems. Please read the INSTALL file for additional information.

Alternatively, it is possible to use ‘pkg-config’ (a file ‘mpfr.pc’ is provided as of MPFR 4.0):

cc myprogram.c $(pkg-config --cflags --libs mpfr)

Note that the ‘MPFR_’ and ‘mpfr_’ prefixes are reserved for MPFR. As a general rule, in order to avoid clashes, software using MPFR (directly or indirectly) and system headers/libraries should not define macros and symbols using these prefixes.