### 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`.