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div, ldiv, lldiv, imaxdiv

From cppreference.com
< c‎ | numeric‎ | math
 
 
 
Common mathematical functions
Types
div_tldiv_tlldiv_timaxdiv_t
(C99)(C99)    

(C99)(C99)    

Functions
Basic operations
divldivlldivimaxdiv
(C99)(C99)
(C99)
(C99)
(C99)
(C99)(C99)(C99)(C23)
Maximum/minimum operations
(C99)
(C23)    
Exponential functions
(C23)
(C99)
(C99)
(C23)
(C23)
(C99)
(C99)(C23)
(C23)
(C23)
Power functions
(C99)
(C23)
(C23)
(C99)
(C23)
(C23)
Trigonometric and hyperbolic functions
(C23)
(C23)
(C23)
(C23)
(C99)
(C99)
(C99)
Error and gamma functions
(C99)
(C99)
(C99)
(C99)
Nearest integer floating-point operations
(C99)(C99)(C99)
(C99)
(C99)(C99)(C99)
(C23)(C23)(C23)(C23)
Floating-point manipulation functions
(C99)(C99)
(C99)(C23)
(C99)
Narrowing operations
(C23)
(C23)
(C23)
(C23)
(C23)
(C23)
Quantum and quantum exponent functions
Decimal re-encoding functions
Total order and payload functions
Classification
(C99)
(C99)
(C99)
(C23)
Macro constants
Special floating-point values
(C99)(C23)
Arguments and return values
(C99)(C99)(C99)(C99)(C99)    
Error handling
(C99)    

 
Defined in header <stdlib.h>
div_t     div( int x, int y );
(1)
ldiv_t    ldiv( long x, long y );
(2)
lldiv_t   lldiv( long long x, long long y );
(3) (since C99)
Defined in header <inttypes.h>
imaxdiv_t imaxdiv( intmax_t x, intmax_t y );
(4) (since C99)

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

Computes quotient and remainder simultaneously. The quotient is the algebraic quotient with any fractional part discarded (truncated towards zero). The remainder is such that quot * y + rem == x.

(until C99)

Computes the quotient (the result of the expression x / y) and remainder (the result of the expression x % y) simultaneously.

(since C99)

Contents

[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, intmax_t, respectively), returns both as an object of type div_t, ldiv_t, lldiv_t, imaxdiv_t defined as follows:

div_t

struct div_t { int quot; int rem; };

or

struct div_t { int rem; int quot; };

ldiv_t

struct ldiv_t { long quot; long rem; };

or

struct ldiv_t { long rem; long quot; };

lldiv_t

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

or

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

imaxdiv_t

struct imaxdiv_t { intmax_t quot; intmax_t rem; };

or

struct imaxdiv_t { intmax_t rem; intmax_t quot; };

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

[edit] Notes

Until C99, 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 div and ldiv.

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

#include <assert.h>
#include <limits.h>
#include <math.h>
#include <stdio.h>
#include <stdlib.h>
 
void reverse(char* first, char* last)
{
    for (--last; first < last; ++first, --last)
    {
        char c = *last;
        *last = *first;
        *first = c;
    }
}
 
// returns empty buffer in case of buffer overflow
char* itoa(int n, int base, char* buf, size_t buf_size)
{
    assert(2 <= base && base <= 16 && buf && buf_size);
    div_t dv = {.quot = n};
    char* p = buf;
    do
    {
        if (!--buf_size)
            return (*buf = '\0'), buf;
        dv = div(dv.quot, base);
        *p++ = "0123456789abcdef"[abs(dv.rem)];
    }
    while(dv.quot);
    if (n < 0)
        *p++ = '-';
    *p = '\0';
    reverse(buf, p);
    return buf;
}
 
int main(void)
{
    char buf[16];
    printf("%s\n", itoa(0, 2, buf, sizeof buf));
    printf("%s\n", itoa(007, 3, buf, sizeof buf));
    printf("%s\n", itoa(12346, 10, buf, sizeof buf));
    printf("%s\n", itoa(-12346, 10, buf, sizeof buf));
    printf("%s\n", itoa(-42, 2, buf, sizeof buf));
    printf("%s\n", itoa(INT_MAX, 16, buf, sizeof buf));
    printf("%s\n", itoa(INT_MIN, 16, buf, sizeof buf));
}

Possible output:

0
21
12346
-12346
-101010
7fffffff
-80000000

[edit] References

  • C23 standard (ISO/IEC 9899:2023):
  • 7.8.2.2 The imaxdiv function (p: TBD)
  • 7.22.6.2 The div, ldiv and lldiv functions (p: TBD)
  • C17 standard (ISO/IEC 9899:2018):
  • 7.8.2.2 The imaxdiv function (p: 159)
  • 7.22.6.2 The div, ldiv and lldiv functions (p: 259)
  • C11 standard (ISO/IEC 9899:2011):
  • 7.8.2.2 The imaxdiv function (p: 219)
  • 7.22.6.2 The div, ldiv and lldiv functions (p: 356)
  • C99 standard (ISO/IEC 9899:1999):
  • 7.8.2.2 The imaxdiv function (p: 200)
  • 7.20.6.2 The div, ldiv and lldiv functions (p: 320)
  • C89/C90 standard (ISO/IEC 9899:1990):
  • 4.10 div_t, ldiv_t
  • 4.10.6.2 The div function
  • 4.10.6.4 The ldiv function

[edit] See also

(C99)(C99)
computes remainder of the floating-point division operation
(function) [edit]
computes signed remainder of the floating-point division operation
(function) [edit]
(C99)(C99)(C99)
computes signed remainder as well as the three last bits of the division operation
(function) [edit]

[edit] External links

1.  Euclidean division — From Wikipedia.
2.  Modulo (and Truncated division) — From Wikipedia.