12.2 C++ Interface Integers

Function: mpz_class::mpz_class (type n)

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).

Function: explicit mpz_class::mpz_class (const mpz_t z)

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.

Function: explicit mpz_class::mpz_class (const char *s, int base = 0)

Function: explicit mpz_class::mpz_class (const string& s, int base = 0)

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=.

Function: mpz_class operator"" _mpz (const char *str)

With C++11 compilers, integers can be constructed with the syntax 123_mpz which is equivalent to mpz_class("123").

Function: mpz_class operator/ (mpz_class a, mpz_class d)

Function: mpz_class operator% (mpz_class a, mpz_class d)

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());

Function: mpz_class abs (mpz_class op)

Function: int cmp (mpz_class op1, type op2)

Function: int cmp (type op1, mpz_class op2)

Function: bool mpz_class::fits_sint_p (void)

Function: bool mpz_class::fits_slong_p (void)

Function: bool mpz_class::fits_sshort_p (void)

Function: bool mpz_class::fits_uint_p (void)

Function: bool mpz_class::fits_ulong_p (void)

Function: bool mpz_class::fits_ushort_p (void)

Function: double mpz_class::get_d (void)

Function: long mpz_class::get_si (void)

Function: string mpz_class::get_str (int base = 10)

Function: unsigned long mpz_class::get_ui (void)

Function: int mpz_class::set_str (const char *str, int base)

Function: int mpz_class::set_str (const string& str, int base)

Function: int sgn (mpz_class op)

Function: mpz_class sqrt (mpz_class op)

Function: mpz_class gcd (mpz_class op1, mpz_class op2)

Function: mpz_class lcm (mpz_class op1, mpz_class op2)

Function: void mpz_class::swap (mpz_class& op)

Function: void swap (mpz_class& op1, mpz_class& op2)

These functions provide a C++ class interface to the corresponding GMP C routines.

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.