std::div,std::ldiv,std::lldiv (3) - Linux Man Pages

std::div,std::ldiv,std::lldiv: std::div,std::ldiv,std::lldiv


std::div,std::ldiv,std::lldiv - std::div,std::ldiv,std::lldiv


Defined in header <cstdlib>
std::div_t div( int x, int y ); (1)
std::ldiv_t div( long x, long y ); (2)
std::lldiv_t div( long long x, long long y ); (3) (since C++11)
std::ldiv_t ldiv( long x, long y ); (4)
std::lldiv_t lldiv( long long x, long long y ); (5) (since C++11)
Defined in header <cinttypes>
std::imaxdiv_t div( std::intmax_t x, std::intmax_t y ); (6) (since C++11)
std::imaxdiv_t imaxdiv( std::intmax_t x, std::intmax_t y ); (7) (since C++11)

Computes both the quotient and the remainder of the division of the numerator x by the denominator y

The quotient is the algebraic quotient with any fractional part discarded (truncated towards zero). The remainder is such that quot * y + rem == x. (until C++11)
The quotient is the result of the expression x/y. The remainder is the result of the expression x%y. (since C++11)


x, y - integer values

Return value

If both the remainder and the quotient can be represented as objects of the corresponding type (int, long, long long, std::imaxdiv_t, respectively), returns both as an object of type std::div_t, std::ldiv_t, std::lldiv_t, std::imaxdiv_t defined as follows:


  struct div_t { int quot; int rem; };


  struct div_t { int rem; int quot; };


  struct ldiv_t { long quot; long rem; };


  struct ldiv_t { long rem; long quot; };


  struct lldiv_t { long long quot; long long rem; };


  struct lldiv_t { long long rem; long long quot; };


  struct imaxdiv_t { std::intmax_t quot; std::intmax_t rem; };


  struct imaxdiv_t { std::intmax_t rem; std::intmax_t quot; };

If either the remainder or the quotient cannot be represented, the behavior is undefined.


Until C++11, the rounding direction of the quotient and the sign of the remainder in the built-in_division_and_remainder_operators was implementation-defined if either of the operands was negative, but it was well-defined in std::div.
On many platforms, a single CPU instruction obtains both the quotient and the remainder, and this function may leverage that, although compilers are generally able to merge nearby / and % where suitable.


// Run this code

  #include <string>
  #include <cmath>
  #include <cstdlib>
  #include <iostream>

  std::string itoa(int n, int base)
      std::string buf;
      std::div_t dv{}; dv.quot = n;
      do {
          dv = std::div(dv.quot, base);
          buf += "0123456789abcdef"[std::abs(dv.rem)]; // string literals are arrays
      } while(dv.quot);
      if(n<0) buf += '-';
      return {buf.rbegin(), buf.rend()};

  int main()
      std::cout << itoa(12345, 10) << '\n'
                << itoa(-12345, 10) << '\n'
                << itoa(65535, 16) << '\n';



See also

fmodl remainder of the floating point division operation


remainderl signed remainder of the division operation

remquol signed remainder as well as the three last bits of the division operation