Support for variable-length arrays (incomplete arrays) in C 99

 

In standard C or C ++, int array [0]; is invalid because it does not support arrays with a length of 0. However, some compiler Extensions support arrays with a length of 0.

 

In C, the 0-length array is mainly used as the last member of the struct, then use it to access a piece of memory after the struct object (usually the dynamically allocated memory ). Due to its non-standard nature, avoid using an array of 0 length in the program. As a replacement, you can use an incomplete array in the C99 standard to replace the array definition with a length of 0. For example:

 

Struct X {

/* Members */

Int array [];/* Do not write int array [0]; since it is not standard .*/

};

General applications:

 

 

Struct {

Int a, B;

Char data [0];

/* Do not write fields below */

};

 

Struct A * p;

 

Int n= 100, I;

P = malloc (sizeof (struct A) + n );

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

P-> data [I] = 1;

 

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