Subject: [LI] Some C++ doubts

["Pankaj Mathur" <matsulsan@xxxxxxxxxxx>]

Hi Sridhar,
This is very simple to explain. Normally in a function definition you 
precede the declaration with a int/float/string /char/void etc, this 
declares the type that the function will be returning after finishing its 
assigned work. But a constructor is a special function which is not supposed 
to return anything - to avoid confusion you are not even allowed to use 
"void" for its declaration. In the first case you are trying to return 
something from a function which is not supposed to return anything- hence 
you will get compile time error.. In second case it is working fine because 
you are making a normal call to the constructor and then returning another 
valid argument (temp in your case). Coming back to your case - a constructor 
is not supposed to return anything is also a very fundamental aspect of OOP. 
A constructor is called whenever an instance of an object needs to be 
instantiated - so unless the object has been created succesfully it has got 
no meaning to expect it to return something. And if it failed to creat an 
instance of an object successfully then also your code will not work as the 
required object has not been created. But sometimes you need to know the 
status of outcome of constructor so here is what you can do- include a 
statement like `cout<<"ALL OK" ' in your constructor code(this will be 
displayed only if the object has been instantiated succesfully).Include a 
"throw-catch" code for handling the appropriate exception in your 
constructor code. Now this code will be executed only in the event of 
constructor failing to instantiate an object. Your main code execution 
cannot proceed because the required object has not been constructed 
succesfully so the `exception handling ' gives you the flexibilty to recover 
from such hopeless situations.
HTH
Pankaj Mathur
Bangkok

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>  1)An error is encountered when constructor is involved in return
>statement. e.g. following statement is not allowed
>    return(Vector ftemp(temp));
 >But following thing works.
>    Vector ftemp(temp);
>    return(temp);
>    Shridhar
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