20.2 Integer Division

This section describes functions for performing integer division. These functions are redundant when GNU CC is used, because in GNU C the ‘/’ operator always rounds towards zero. But in other C implementations, ‘/’ may round differently with negative arguments. div and ldiv are useful because they specify how to round the quotient: towards zero. The remainder has the same sign as the numerator.

These functions are specified to return a result r such that the value r.quot*denominator + r.rem equals numerator.

To use these facilities, you should include the header file stdlib.h in your program.

Data Type: div_t

This is a structure type used to hold the result returned by the div function. It has the following members:

int quot

The quotient from the division.

int rem

The remainder from the division.

Function: div_t div (int numerator, int denominator)

Preliminary: | MT-Safe | AS-Safe | AC-Safe | See POSIX Safety Concepts.

This function div computes the quotient and remainder from the division of numerator by denominator, returning the result in a structure of type div_t.

If the result cannot be represented (as in a division by zero), the behavior is undefined.

Here is an example, albeit not a very useful one.

div_t result;
result = div (20, -6);

Now result.quot is -3 and result.rem is 2.

Data Type: ldiv_t

This is a structure type used to hold the result returned by the ldiv function. It has the following members:

long int quot

The quotient from the division.

long int rem

The remainder from the division.

(This is identical to div_t except that the components are of type long int rather than int.)

Function: ldiv_t ldiv (long int numerator, long int denominator)

Preliminary: | MT-Safe | AS-Safe | AC-Safe | See POSIX Safety Concepts.

The ldiv function is similar to div, except that the arguments are of type long int and the result is returned as a structure of type ldiv_t.

Data Type: lldiv_t

This is a structure type used to hold the result returned by the lldiv function. It has the following members:

long long int quot

The quotient from the division.

long long int rem

The remainder from the division.

(This is identical to div_t except that the components are of type long long int rather than int.)

Function: lldiv_t lldiv (long long int numerator, long long int denominator)

Preliminary: | MT-Safe | AS-Safe | AC-Safe | See POSIX Safety Concepts.

The lldiv function is like the div function, but the arguments are of type long long int and the result is returned as a structure of type lldiv_t.

The lldiv function was added in ISO C99.

Data Type: imaxdiv_t

This is a structure type used to hold the result returned by the imaxdiv function. It has the following members:

intmax_t quot

The quotient from the division.

intmax_t rem

The remainder from the division.

(This is identical to div_t except that the components are of type intmax_t rather than int.)

See Integers for a description of the intmax_t type.

Function: imaxdiv_t imaxdiv (intmax_t numerator, intmax_t denominator)

Preliminary: | MT-Safe | AS-Safe | AC-Safe | See POSIX Safety Concepts.

The imaxdiv function is like the div function, but the arguments are of type intmax_t and the result is returned as a structure of type imaxdiv_t.

See Integers for a description of the intmax_t type.

The imaxdiv function was added in ISO C99.