Best way to exit a C++ Class Constructor

MrPickle

The title says it all really?

What's the best way to exit a class constructor?

zodilla58

Can you explain your question a bit more? When any object is created constructor is called...! What is inside your constructor class? If you can add your code snippet here!

MrPickle

Well in the constructor, say there's an error and I need to exit the constructor, normally you would use return, but because the constructor has return type I cannot use return.

eg:

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#include <iostream>
 
class MyClass

{

   public:

      MyClass(int i);

      int num;

}
 
MyClass::MyClass(int i)

{

   if(i < 10)

   {

      std::cout << "Error! i is less than 10\n";

      //Exit the constructor how?

   }
 
   num = i;

}

Just a quick example.

JosAH

Of course, in your example you can silently set i to 10 and use that value but if there really is no good default value to use, throw an exception. The object won't be constructed then (a handy feature, write that down!) and it is up to the caller to fix it, i.e. either catch the exception and deal with it or die.

kind regards,

Jos

MrPickle

I see lots of different things when I look around at throw.

I see things like:
throw 1;
throw std::runtime_error("Message");

What should I be doing?

JosAH

Quote:

Originally Posted by MrPickle

I see lots of different things when I look around at throw.

I see things like:
throw 1;
throw std::runtime_error("Message");

What should I be doing?

Throw a specific exception; the runtime_error exception has several subclasses that may be more applicable. It also has a sibbling class: 'logic_error'; it's up to you.

kind regards,

Jos

MrPickle

Quote:

Originally Posted by JosAH

Throw a specific exception; the runtime_error exception has several subclasses that may be more applicable. It also has a sibbling class: 'logic_error'; it's up to you.

kind regards,

Jos

Thank you, I will look into that.

Best way to exit a C++ Class Constructor

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