stddef.h File Reference

Define basic data types. More...

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Macros
#define	NULL   ((void *)0)
	Define NULL.
#define	EOF   (-1)
	Define End-Of-File.
#define	BUFSIZ   512
	Define the size of a buffer.
#define	offsetof(type, member)    ((size_t) & (((type *)0)->member))
#define	container_of(ptr, type, member)    ((type *)((char *)(1 ? (ptr) : &((type *)0)->member) - offsetof(type, member)))
	Retrieve an enclosing structure from a pointer to a nested element.
#define	alignof(type)
	Returns the alignment, in bytes, of the specified type. More...
#define	count_of(x)   ((sizeof(x) / sizeof((x)[0])) / ((size_t)(!(sizeof(x) % sizeof((x)[0])))))
	Counts the number of elements of an array.
#define	swap(a, b)
	Swaps two values. More...

Typedefs
typedef long signed int	ptrdiff_t
	Is the signed integer type of the result of subtracting two pointers.
typedef unsigned char	byte_t
	Define the byte type.
typedef unsigned long	size_t
	Define the generic size type.
typedef long	ssize_t
	Define the generic signed size type.
typedef unsigned int	ino_t
	Define the type of an inode.
typedef unsigned int	dev_t
	Used for device IDs.
typedef int	uid_t
	The type of user-id.
typedef int	gid_t
	The type of group-id.
typedef long int	off_t
	The type of offset.
typedef unsigned int	mode_t
	The type of mode.
typedef unsigned int	pgprot_t
	This data-type is used to set protection bits of pages.

Detailed Description

Define basic data types.

Copyright

(c) 2014-2024 This file is distributed under the MIT License. See LICENSE.md for details.

Macro Definition Documentation

alignof

#define alignof

(

type

)

Value:

    offsetof( \
    struct { char c; type member; }, member)

Returns the alignment, in bytes, of the specified type.

offsetof

#define offsetof	(		type,
			member
	)		((size_t) & (((type *)0)->member))

It evaluates to the offset (in bytes) of a given member within a struct or union type, an expression of type size_t.

swap

#define swap	(		a,
			b
	)

Value:

    do {                       \
        typeof(a) temp = (a);  \
        (a)            = (b);  \
        (b)            = temp; \
    } while (0)

Swaps two values.

do { ... } while (0) allows to place multistatement operations, for instance, inside the following if stantement: if (condition) swap(var1, var2) which otherwise would be wrong.