confused with typedefs

[raashid bhatt]

typedef int function(int);

Please explain how can i use this one

 

[Eric Sosman]

typedef int function(int);

Please explain how can i use this one

There's not much you can do with this one. You can
use it in the declaration of a function pointer:

int this(int x) { return x + 1; }
int that(int y) { return y - 1; }
function *fptr = this;
function *gptr = that;

.... but that's about the extent of it. You cannot use
it in the actual definition of a function taking one int
parameter and returning an int value:

function this { return x + 1; } /* no good */

.... because there's no way the typedef can supply the name
of the parameter (no, not even if you write a name in the
typedef itself).

 

[jameskuyper]

There's not much you can do with this one. You can
use it in the declaration of a function pointer:

You can also use it in a declaration of a function:

function this;
function that;

Note that this can be useful if inserted before definitions like the
ones below, because any mismatch between the function definition and
the function declaration will require a diagnostic message.

int this(int x) { return x + 1; }
int that(int y) { return y - 1; }

....

 

[Ben Bacarisse]

You can also use it in a declaration of a function:

function this;
function that;

and it can be used to declare a function parameter where is will be
adjusted to a pointer type (so this is not really another way to use
it all!):

int call_it(function f, int i) { return f(i); }

This style is odd enough that it should probably be discouraged.

<snip>