pointers

[sundaram.bhuvana]

hi
i would like to know about the meaning of the following code

int select(int(*fn)(int,int),int x,int y)

what is the meaning of it

 

[David Côme]

hi
i would like to know about the meaning of the following code

int select(int(*fn)(int,int),int x,int y)

what is the meaning of it

int(*fn)(int,int) is a pointeur to a fonction who return a int and who
takes 2 ints for parameters

 

[Abhishek Padmanabh]

int(*fn)(int,int) is a pointeur to a fonction who return a int and who  
takes 2 ints for parameters

... and select is a function that takes that takes 3 arguments, first
being the pointer to the function as described by David above and 2
integers and has a return type : int.

 

[Howard]

i would like to know about the meaning of the following code

int select(int(*fn)(int,int),int x,int y)

It's a function (select), which returns an int, and which takes three
parameters; the last two parameters are ints (x and y), and the first
parameter is a pointer to a function (fn) which returns an int and takes two
int parameters.

(Personally, I'd prefer to create a typedef for the function pointer, and
put that type in the parameter list, just to make it more readable.)

-Howard

 

[Daniel T.]

It's a function (select), which returns an int, and which takes three
parameters; the last two parameters are ints (x and y), and the first
parameter is a pointer to a function (fn) which returns an int and takes two
int parameters.

(Personally, I'd prefer to create a typedef for the function pointer, and
put that type in the parameter list, just to make it more readable.)

And since this is a C++ newsgroup, I think making it a template would
be more approprate.

 

[Dave Rahardja]

And since this is a C++ newsgroup, I think making it a template would
be more approprate.

How so?

-dr

 

[Kira Yamato]

How so?

-dr

template<typename F>
int select(F f, int x, int y)
{
// for example,
return f(x,y);
}

 

[Daniel T.]

How so?

The same way it is done in the standard library. Note that 'fn' in the
above satisfies the Binary Function concept and could be used in (for
example) std::transform.

template < typename Fn >
int select( Fn fn, int x, int y )
{
// now use 'fn' under the assumption that it takes two ints as
// arguments and returns an int. For example like this:

return fn( x, y );
}

 

[Rahul]

hi
i would like to know about the meaning of the following code

int select(int(*fn)(int,int),int x,int y)

what is the meaning of it

Have a look at http://www.codeproject.com/KB/cpp/complex_declarations.aspx?print=true
for a better understanding...

 

[Carlo Milanesi]

(e-mail address removed) ha scritto:

hi
i would like to know about the meaning of the following code

int select(int(*fn)(int,int),int x,int y)

It is a declaration of the function "select", as a function taking three
formal parameters, "fn", "x", and "y", and returning an "int".
The first of such parameters ("fn") is a pointer to a function that
takes two parameters, both of type "int", and returns an "int". The
second and third parameters ("x" and "y") are of type "int".