What happens when I declare say multiple variables on a single line? e.g.
int x, y, z;
All are ints. The question is what are y and z in the following statement?
int* x, y, z;
Are they all int pointers?
Only x
is a pointer to int; y
and z
are regular ints.
This is one aspect of C declaration syntax that trips some people up. C uses the concept of a declarator, which introduces the name of the thing being declared along with additional type information not provided by the type specifier. In the declaration
int* x, y, z;
the declarators are *x
, y
, and z
(it's an accident of C syntax that you can write either int* x
or int *x
, and this question is one of several reasons why I recommend using the second style). The int-ness of x
, y
, and z
is specified by the type specifier int
, while the pointer-ness of x
is specified by the declarator *x
(IOW, the expression *x
has type int
).
If you want all three objects to be pointers, you have two choices. You can either declare them as pointers explicitly:
int *x, *y, *z;
or you can create a typedef for an int pointer:
typedef int *iptr;
iptr x, y, z;
Just remember that when declaring a pointer, the *
is part of the variable name, not the type.