std::div, std::ldiv, std::lldiv - cppreference.com

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

From cppreference.com
< cpp‎ | numeric‎ | math

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)

### [edit] Parameters

x, y | - | integer values

### [edit] 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::ldiv_t`, `std::imaxdiv_t` defined as follows:

# std::div_t

    struct div_t { int quot; int rem; };

or

    struct div_t { int rem; int quot; };

# std::ldiv_t

    struct ldiv_t { long quot; long rem; };

or

    struct ldiv_t { long rem; long quot; };

# std::lldiv_t

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

or

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

# std::imaxdiv_t

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

or

    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.

### [edit] Notes

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.

### [edit] Example

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)];  // the type of the string literal is
                                                          // const char[17]
        } 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';
    }

Output:

    12345
    -12345
    ffff

### [edit] See also

fmod | remainder of the floating point division operation (function) [edit]
remainder (C++11) | signed remainder of the division operation (function) [edit]
remquo (C++11) | signed remainder as well as the three last bits of the division operation (function) [edit]
C documentation for div

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