Assignment of an alternative struct in C Language

 

Looking at the Linux kernel source code over the past few days, it is very strange to see the assignment of the struct variable init_pid_ns.

 

Struct pid_namespace init_pid_ns = {

. Kref = {

. Refcount = ATOMIC_INIT (2 ),

},

. Pidmap = {

[0... PIDMAP_ENTRIES-1] = {ATOMIC_INIT (BITS_PER_PAGE), NULL}

},

. Last_pid = 0,

. Level = 0,

. Child_reaper = & init_task,

};

Note the value assignment form of the struct array. pidmap in the above Code.

 

[0... PIDMAP_ENTRIES-1]

The index is assigned directly, and the index range is written directly. A little python flavor.

 

I just remember that the variable parameters of C-language functions are in the... method. I never thought about this operation method for struct.

 

Interested. I wrote a short piece of similar code myself.

 

# Include <stdio. h>

 

Struct pid {

Int val;

Void * fn;

};

 

Struct str {

Int val;

Struct pid id [10];

};

 

Struct str init_str = {

. Val = 1,

. Id = {

[0... 9] = {2, NULL}

},

};

 

Int main (void ){

Int I;

 

For (I = 0; I <10; I ++)

Printf ("init_str.id [% d]. val = % d \ n", I, init_str.id [I]. val );

 

Return 0;

}

 

Compile and test. The result is true.

 

If you want to operate the struct array, try this method.

 

From wfing