отсортировать таблицу данных (sort a table of data)
Пролог (Prolog)
This manual page is part of the POSIX Programmer's Manual. The
Linux implementation of this interface may differ (consult the
corresponding Linux manual page for details of Linux behavior),
or the interface may not be implemented on Linux.
Имя (Name)
qsort — sort a table of data
Синопсис (Synopsis)
#include <stdlib.h>
void qsort(void *base, size_t nel, size_t width,
int (*compar)(const void *, const void *));
Описание (Description)
The functionality described on this reference page is aligned
with the ISO C standard. Any conflict between the requirements
described here and the ISO C standard is unintentional. This
volume of POSIX.1‐2017 defers to the ISO C standard.
The qsort() function shall sort an array of nel objects, the
initial element of which is pointed to by base. The size of each
object, in bytes, is specified by the width argument. If the nel
argument has the value zero, the comparison function pointed to
by compar shall not be called and no rearrangement shall take
place.
The application shall ensure that the comparison function pointed
to by compar does not alter the contents of the array. The
implementation may reorder elements of the array between calls to
the comparison function, but shall not alter the contents of any
individual element.
When the same objects (consisting of width bytes, irrespective of
their current positions in the array) are passed more than once
to the comparison function, the results shall be consistent with
one another. That is, they shall define a total ordering on the
array.
The contents of the array shall be sorted in ascending order
according to a comparison function. The compar argument is a
pointer to the comparison function, which is called with two
arguments that point to the elements being compared. The
application shall ensure that the function returns an integer
less than, equal to, or greater than 0, if the first argument is
considered respectively less than, equal to, or greater than the
second. If two members compare as equal, their order in the
sorted array is unspecified.
Возвращаемое значение (Return value)
The qsort() function shall not return a value.
Ошибки (Error)
No errors are defined.
The following sections are informative.
Примеры (Examples)
None.
Использование в приложениях (Application usage)
The comparison function need not compare every byte, so arbitrary
data may be contained in the elements in addition to the values
being compared.
Обоснование (Rationale)
The requirement that each argument (hereafter referred to as p)
to the comparison function is a pointer to elements of the array
implies that for every call, for each argument separately, all of
the following expressions are non-zero:
((char *)p - (char *)base) % width == 0
(char *)p >= (char *)base
(char *)p < (char *)base + nel * width
Будущие направления (Future directions)
None.
Смотри также (See also)
alphasort(3p)
The Base Definitions volume of POSIX.1‐2017, stdlib.h(0p)
