small help about the constructor in cpp under windows platform

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sir.

i create a class which containing one default and one parameter constructor..

C#

class cSimple
{
private:
    int icount;
    int iLoopValue;
public:                 //always constructure must be in public
        cSimple()
        {
            icount=0;
        }
        cSimple(int iTemp)
        {
            iLoopValue=iTemp;
        }
        void MyFunction()
        {
            for(;icount<iLoopValue;icount++)
                cout<<"The count value is :"<<icount<<endl;
        }
};

my doubt :

can i create a one single object to make a call to both the constructor..
if i done like that means it not running properly .. can you give the solution/

if it possible to call both the constructor with using single object..

Posted 19-Jul-11 2:45am

Dhanasundhari

Updated 19-Jul-11 3:05am

v2

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Albert Holguin · Answer 1 · 2011-07-19T07:24:00

Solution 2

cSimple()
{
    if(CommonInit() != 0){error handling}
}
cSimple(int iTemp)
{
   if(CommonInit() != 0){error handling}
   iLoopValue=iTemp;
}
int CSimple::CommonInit()
{
  icount = 0;
  iLoopValue = 0; //Don't leave any members uninitialized

  return 0;
}

Posted 19-Jul-11 7:24am

Albert Holguin

Comments

Stefan_Lang 20-Jul-11 5:55am

My 5 as it's the best (and pretty much only sensible) answer I can think of.

KarstenK · Answer 2 · 2011-07-19T02:58:00

Solution 1

you cant call MyFunction() inside the constructor, but this is dangerous if severe errors are happening or no error handling possible

best is default arg:

cSimple(int iTemp = 0)

Posted 19-Jul-11 2:58am

KarstenK

Comments

Dhanasundhari 19-Jul-11 9:03am

sir,, it will execute only the parameter constructor ...

i want execute the default constructor too..
what i want to do..

KarstenK 20-Jul-11 7:12am

What i wrote is defaulting arguments.
Do you this syntax?

cSimple() : icount(0)
{
}

Take my three experieneced advises to your heart:

1. dont run functions in constructors
2. read a basic C++ progemming book like "C++ for dummies"
3. go trouble out of the way so you win without fighting

Stefan_Lang 20-Jul-11 5:56am

There's nothing wrong with calling other member functions in the constructor as long as they're not virtual.

KarstenK 20-Jul-11 7:15am

timing and error handling are bad in constructor. Or would you fetch data from a databse oder search for an update in a constructor?

If you say "YES" THAN "There's nothing wrong with calling other member functions in the constructor as long as they're not virtual."
ELSE "but this is dangerous" :-O

Albert Holguin 20-Jul-11 10:14am

I wouldn't say its dangerous at all... specially in the case of doing initialization... and no, you shouldn't access a database in a constructor...

KarstenK 20-Jul-11 10:21am

and if some "buddy" later is changing the code, that isnt your vault...

YvesDaoust · Answer 3 · 2011-07-19T10:41:00

Solution 3

You can call a constructor explicitly for an already created object:

cSimple myS; // Normal constructor call, creates the object

myS.cSimple::cSimple(134); // Explicit constuctor call on an existing object

This way you can call several constructors on the same object. This not a recommended practice.

Posted 19-Jul-11 10:41am

YvesDaoust

Updated 19-Jul-11 10:45am

v5

Comments

Stefan_Lang 20-Jul-11 5:53am

My 1, because what you intended is not guaranteed to work, and might even crash the program.

Besides the call is syntactically incorrect and shouldn't* even compile. You are calling the constructor as a static function! The call should be:

myS.CSimple(134);

* P.s.: I would have said it *will* not, but some compilers do accept weird code occasionally...

YvesDaoust 20-Jul-11 11:01am

Then the 1 goes to Visual C++ 2003.

The scoped version does compile and run. The straight version does not compile. (error C2274: 'function-style cast' : illegal as right side of '.' operator)