CODEWITHSUNDEEP
cdeclarationdefinition
George Newton
George Newton

Reputation: 3303

Is this a definition in C?

According to the C standard, this is considered a definition

int x;

Because it declares x and allocates storage. But is this also a definition?

int *x;

That is, does declaring a pointer variable or array variable allocate storage? I'm guessing no because we have to use malloc.

Upvotes: 2

Views: 103

Answers (2)

sepp2k
sepp2k

Reputation: 370455

int* x; is a definition. It allocates storage to store the pointer. It does not allocate any storage for an integer - that's why you need malloc if you don't want to point to an existing variable (or other memory location).

A pure declaration would be something like extern int x; or extern int* x;, which would then have a corresponding definition in a different compilation unit.

Upvotes: 6

HelloWorld123456789
HelloWorld123456789

Reputation: 5369

int *x; allocates storage. Variable x is allocated storage equal to sizeof(int *). It contains a garbage value if it's at block scope or a null pointer value if it's at file scope.

Upvotes: 4

Related Questions