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

 

C++

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Technical Specifications

 

Numerics library

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Common mathematical functions

Functions
Basic operations
abs(int)labsllabsimaxabs (C++11) abs(float)fabs divldivlldivimaxdiv (C++11) fmod	remainder (C++11) remquo (C++11) fma (C++11) fmax (C++11) fmin (C++11) fdim (C++11) nannanfnanl (C++11)(C++11)(C++11)
Exponential functions
exp exp2 (C++11) expm1 (C++11)	log log10 log1p (C++11) log2 (C++11)
Power functions
sqrt cbrt (C++11)	hypot (C++11) pow
Trigonometric and hyperbolic functions
sin cos tan asin acos atan atan2	sinh cosh tanh asinh (C++11) acosh (C++11) atanh (C++11)

Error and gamma functions
erf (C++11) erfc (C++11)	lgamma (C++11) tgamma (C++11)
Nearest integer floating point operations
ceil floor roundlroundllround (C++11)(C++11)(C++11)	trunc (C++11) nearbyint (C++11) rintlrintllrint (C++11)(C++11)(C++11)
Floating point manipulation functions
ldexp scalbnscalbln (C++11)(C++11) ilogb (C++11) logb (C++11)	frexp modf nextafternexttoward (C++11)(C++11) copysign (C++11)
Classification/Comparison
fpclassify (C++11) isfinite (C++11) isinf (C++11) isnan (C++11) isnormal (C++11) signbit (C++11)	isgreater (C++11) isgreaterequal (C++11) isless (C++11) islessequal (C++11) islessgreater (C++11) isunordered (C++11)
Macro constants
HUGE_VALFHUGE_VALHUGE_VALL (C++11)(C++11) INFINITY (C++11) NAN (C++11) math_errhandlingMATH_ERRNOMATH_ERREXCEPT (C++11)	FP_NORMALFP_SUBNORMALFP_ZEROFP_INFINITEFP_NAN (C++11)(C++11)(C++11)(C++11)(C++11)

 

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)

Parameters

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:

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.

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.

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)];  // 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';
}

Output:

12345
-12345
ffff

See also

fmodfmodffmodl (C++11)(C++11)	remainder of the floating point division operation (function)
remainderremainderfremainderl (C++11)(C++11)(C++11)	signed remainder of the division operation (function)
remquoremquofremquol (C++11)(C++11)(C++11)	signed remainder as well as the three last bits of the division operation (function)