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(gmp.info)C++ Formatted Output

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C++ Formatted Output
====================

   The following functions are provided in `libgmpxx', which is built
if C++ support is enabled (Note: Build Options).  Prototypes are
available from `<gmp.h>'.

 - Function: ostream& operator<< (ostream& STREAM, mpz_t OP)
     Print OP to STREAM, using its `ios' formatting settings.
     `ios::width' is reset to 0 after output, the same as the standard
     `ostream operator<<' routines do.

     In hex or octal, OP is printed as a signed number, the same as for
     decimal.  This is unlike the standard `operator<<' routines on
     `int' etc, which instead give twos complement.

 - Function: ostream& operator<< (ostream& STREAM, mpq_t OP)
     Print OP to STREAM, using its `ios' formatting settings.
     `ios::width' is reset to 0 after output, the same as the standard
     `ostream operator<<' routines do.

     Output will be a fraction like `5/9', or if the denominator is 1
     then just a plain integer like `123'.

     In hex or octal, OP is printed as a signed value, the same as for
     decimal.  If `ios::showbase' is set then a base indicator is shown
     on both the numerator and denominator (if the denominator is
     required).

 - Function: ostream& operator<< (ostream& STREAM, mpf_t OP)
     Print OP to STREAM, using its `ios' formatting settings.
     `ios::width' is reset to 0 after output, the same as the standard
     `ostream operator<<' routines do.  The decimal point follows the
     current locale, on systems providing `localeconv'.

     Hex and octal are supported, unlike the standard `operator<<'
     routines on `double' etc.  The mantissa will be in hex or octal,
     the exponent will be in decimal.  For hex the exponent delimiter
     is an `@'.  This is as per `mpf_out_str'.  `ios::showbase' is
     supported, and will put a base on the mantissa.

   These operators mean that GMP types can be printed in the usual C++
way, for example,

     mpz_t  z;
     int    n;
     ...
     cout << "iteration " << n << " value " << z << "\n";

   But note that `ostream' output (and `istream' input, Note: C++
Formatted Input) is the only overloading available and using for
instance `+' with an `mpz_t' will have unpredictable results.