div, ldiv, lldiv, imaxdiv
Defined in header <stdlib.h> | ||
div_t div(int x, int y ); | (1) | |
ldiv_t ldiv(long x, long y ); | (2) | |
lldiv_t lldiv(longlong x, longlong y ); | (3) | (since C99) |
Defined in header <inttypes.h> | ||
| (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, longlong, 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 {longlong quot;longlong rem;};
or
struct lldiv_t {longlong rem;longlong quot;};
imaxdiv_t
or
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 overflowchar* 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 9899:2024):
- 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
[edit]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 | |
[edit]External links
| 1. | Euclidean division — From Wikipedia. |
| 2. | Modulo (and Truncated division) — From Wikipedia. |
