Re: Simple functor

From:
 CodeGrommet <rick.softly@gmail.com>
Newsgroups:
comp.lang.c++
Date:
Tue, 21 Aug 2007 05:16:36 -0700
Message-ID:
<1187698596.220745.211780@r34g2000hsd.googlegroups.com>
On Aug 21, 2:05 pm, Neelesh Bodas <neelesh.bo...@gmail.com> wrote:

On Aug 21, 4:59 pm, CodeGrommet <rick.sof...@gmail.com> wrote:

Hi. Please excuse this post. I searched functor in this group and
had around 1600 hits. The first page couldn't help me. Would someone
be so kind as to look at this code and tell me why it won't compile?
I'm using a mingW compiler.

******************************code*************************************=

****=AD***

#include <iostream>
using namespace std;

class mySquare
{
    public:
    int operator()(int x) const { return x * x; }

}


missing semicolon

int main(){
    cout<<mySquare(2)<<endl;


 non-static function should only be called on object. Here you are
trying to invoke a non-existant unary constructor of mySquare class.

Do this:

    mySquare m;
    cout<< m(2) <<endl;

Or this:

   cout<< mySquare()(2) <<endl;

-N


Yes, I got. Thanks for the reply. The working code looks like this:

#include <iostream>
using namespace std;

class mySquare
{
    public:
    int operator()(int x) const { return x * x; }
};

int main(){
    mySquare s;
    cout<<s(2)<<endl;
    return 0;
}

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