What is the scope of variables declared in a class constructor?

Question

I was curious, what is the scope of variables declared inside a class constructor which are not data members of that class?

For example, if a constructor needs an iterating int i, will this variable be destroyed after the constructor finishes, or is it then global for the program?

Solution 1

In this sense a constructor is like any other function - any variable declared inside has usual scope limitations and they all surely go out of scope and get destroyed once constructor is finished.

Solution 2

Like any other function, if it's a local variable it will be "destroyed" at the end of the function. Local scope.

Solution 3

As it often happens, you could be mixing the notions of scope and lifetime, so I'll address both.

The scope of a name declared inside a constructor is the same as the scope of any local name (the fact that it is a constructor makes no difference whatsoever): the scope of the name extends to the end of the block in which the name is declared (and it can have "holes" when the name is hidden by a declaration of an even "more local" entify with the same name).

The lifetime of am object defined inside a constructor is governed by the same rules as the lifetime of any locally-defined object (the fact that it is a constructor makes no difference whatsoever): an object with automatic storage duration is destroyed at the end of its scope, while an object with static storage duration lives forever.

Solution 4

Variables declared in the class constructor are available inside the scope of the class constructor and nowhere higher.

public MyClass() {
   int i = 0; // i is only available inside this constructor.
              // It can't be used in any other function of this class or any other.
}

Solution 5

Local variables, regardless of the function, are destroyed when they go out of scope. They do not become 'global.'

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Comments

[Tony R]

Thanks! I just wasn't sure if the constructor was considered as a normal function.

[AnT stands with Russia]

No entirely accurate. Objects defined with static storage duration go out of scope, but don't get destroyed once the constructor is finished.

[Caleth]

@AnT how does that differ from statics in any other function?