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Construct an mpz_class
. All the standard C++ types may be used, except
long long
and long double
, and all the GMP C++ classes can be
used, although conversions from mpq_class
and mpf_class
are
explicit
. Any necessary conversion follows the corresponding C
function, for example double
follows mpz_set_d
(see Assigning Integers).
Construct an mpz_class
from an mpz_t
. The value in z is
copied into the new mpz_class
, there won’t be any permanent association
between it and z.
Construct an mpz_class
converted from a string using mpz_set_str
(see Assigning Integers).
If the string is not a valid integer, an std::invalid_argument
exception is thrown. The same applies to operator=
.
With C++11 compilers, integers can be constructed with the syntax
123_mpz
which is equivalent to mpz_class("123")
.
Divisions involving mpz_class
round towards zero, as per the
mpz_tdiv_q
and mpz_tdiv_r
functions (see Integer Division).
This is the same as the C99 /
and %
operators.
The mpz_fdiv…
or mpz_cdiv…
functions can always be called
directly if desired. For example,
mpz_class q, a, d; ... mpz_fdiv_q (q.get_mpz_t(), a.get_mpz_t(), d.get_mpz_t());
These functions provide a C++ class interface to the corresponding GMP C
routines. Calling factorial
or primorial
on a negative number
is undefined.
cmp
can be used with any of the classes or the standard C++ types,
except long long
and long double
.
Overloaded operators for combinations of mpz_class
and double
are provided for completeness, but it should be noted that if the given
double
is not an integer then the way any rounding is done is currently
unspecified. The rounding might take place at the start, in the middle, or at
the end of the operation, and it might change in the future.
Conversions between mpz_class
and double
, however, are defined
to follow the corresponding C functions mpz_get_d
and mpz_set_d
.
And comparisons are always made exactly, as per mpz_cmp_d
.
Next: C++ Interface Rationals, Previous: C++ Interface General, Up: C++ Class Interface [Index]