The attribute in GUN C

A major feature of GNU C is the __attribute__ mechanism. __attribute__ can set function properties (functionsattribute), variable properties (Variable attribute), and

The type attribute (Attribute).

__attribute__ writing features are:There are two underscores before and after the __attribute__, and the next one is immediately followed by a pair of original brackets, the corresponding __attribute__ parameters in parentheses.

__ATTRIBUTE__ syntax Format:__attribute__ ((attribute-list))

Its position constraint is placed before the end of the declaration ";".

Keyword __attribute__ You can alsoset property settings for a struct (struct) or a common body (Union). There are roughly six parameter values that can be set, namely:aligned, packed,

Transparent_union, unused, deprecated and may_alias.

When using the __attribute__ parameter, you can also add "__" (two underscores) before and after the parameter, for example, using __aligned__ instead of aligned, so You can use it in the corresponding header file without worrying about whether there is a macro definition with the same name in the header file.

Aligned (alignment)

This property sets a gill (in bytes) of the specified size, for example:

struct S {

Short b[3];

} __attribute__ ((aligned (8)));

typedef int INT32_T __ATTRIBUTE__ ((aligned (8)));

Http://www.cnblogs.com/astwish/p/3460618.html

The attribute in GUN C