div, ldiv, lldiv, imaxdiv
| Defined in header <stdlib.h>
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| 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>
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| (4) | (since C99) | |
Computes both the quotient and the remainder of the division of the numerator x by the denominator y.
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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) |
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Computes the quotient (the result of the expression x / y) and remainder (the result of the expression x % y) simultaneously. |
(since C99) |
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, 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
or
If either the remainder or the quotient cannot be represented, the behavior is undefined.
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.
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
References
- C23 standard (ISO/IEC 9899:2024):
- 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
See also
| (C99)(C99) |
computes remainder of the floating-point division operation (function) |
| (C99)(C99)(C99) |
computes signed remainder of the floating-point division operation (function) |
| (C99)(C99)(C99) |
computes signed remainder as well as the three last bits of the division operation (function) |
| C++ documentation for div
| |
External links
| 1. | Euclidean division — From Wikipedia. |
| 2. | Modulo (and Truncated division) — From Wikipedia. |