The difference between GNU C and ANSI C

Reference: http://tsroad.lofter.com/post/376316_57ac519

1.GNU C defines a 0-length array, which is intended to define variable-length structures.

struct VAR_STRUCT
{
int Len;
Char data[0];
};

The data of this structure is immediately followed and can be accessed using Data[index].

2.case can range match, case x...y

Switch (n)
{
Case 0...9 C=1;break;
Case 10...11 C=2;break;
...
}

3.GNU c the statement in curly braces as an expression that can appear where any expression can appear

#define Int_min (x, y) \
{int __x= (x); int __y= (y); __x<__y?__x:__y;}

4.typeof keyword, you can get the type of the variable

int x;
typeof (x) y;

5. Macros that support variable parameters

#define DPRINT (Fmt,arg ...) \
PRINTK (fmt,# #arg)

6. Current function name, using macro __function__

7. When initializing a struct or array, the initialization values are allowed to appear in any order by index and struct name.

int s[5]={[0 ... 3]=3,[4]=1};

Note [0 spaces ... Space 3]

struct X
{
int A;
Char b;
};
struct x y=
{
. b= ' h ',
. a=10,
};

8. Allows the declaration of functions, variables, types of special properties, as long as the following add __atribute__ ((attribute))

#define Attri_noreturn __attribute__ ((noreturn))

void exit () Attri_noreturn
{
...
}

9.GNU C provides a large number of built-in functions

10. Use the Do ... while (0) to define the macro to facilitate the addition of the macro;

#define XXX Do{free (p);p =null;} while (0)

11. Error handling is often done with goto statements.

The above is from "Linux device driver development details".

The difference between GNU C and ANSI C