Class Quiz-Asked in Interviews

How can we make a C++ class such that objects of it can only be created using a new operator? If a user tries to create an object directly, the program produces a compiler error.

A) Not Possible

B) By making destructor private

C) By making constructor private

D) By making both constructor and destructor private

Solution:

B) is Correct

This code snippet explains the solution

// Objects of test can only be created using new
class Test
{
private:
    ~Test() {}
friend void destructTest(Test* );
};
 
// Only this function can destruct objects of Test
void destructTest(Test* ptr)
{
    delete ptr;
}
 
int main()
{
    // create an object
    Test *ptr = new Test;
 
    // destruct the object
    destructTest (ptr);
 
    return 0;
}

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