This set of Object Oriented Programming (OOPs) using C++ Multiple Choice Questions & Answers (MCQs) focuses on “Object Array”.
1. What is an array of objects?
a) An array of instances of class represented by single name
b) An array of instances of class represented by more than one name
c) An array of instances which have more than 2 instances
d) An array of instances which have different types
Explanation: The array of objects an array of instances of a class. The array is represented by a single name. The array name is itself a pointer. Array name represents the first object.
2. Which among the following is a mandatory condition for array of objects?
a) All the objects should be of different class
b) All the objects should be of same program classes
c) All the objects should be of same class
d) All the objects should have different data
Explanation: The objects of an array must be of same class. This is mandatory because array is set of same type of elements. The objects of same class are considered to be of same type.
3. What is the type of elements of array of objects?
Explanation: The class itself is the type of elements of array of objects. All the objects possess the same properties. Like any other primitive data type, the objects are of their respective class type.
4. If array of objects is declared as given below, which is the limitation on objects?
a) The objects will have same values
b) The objects will not be initialized individually
c) The objects can never be initialized
d) The objects will have same data
Explanation: If the syntax given, is used to declare the array of objects, then the objects can’t be initialized individually. All the objects will have to be initialized after this declaration.
5. Which is the condition that must be followed if the array of objects is declared without initialization, only with size of array?
a) The class should have separate constructor for each object
b) The class must have no constructors
c) The class should not have any member function
d) The class must have a default or zero argument constructor
Explanation: The class must have a default/zero argument constructor. Since the declaration is done by only specifying the size of array, the class must have default a construct to be called by default to reserve memory for each object. Also, we can’t specify the arguments in this type of declaration hence the class should provide a default initialization.
6. When are the array of objects without any initialization useful?
a) When object data is not required just after the declaration
b) When initialization of object data is to be made by the compiler
c) When object data doesn’t matter in the program
d) When the object should contain garbage data
Explanation: Sometimes the object data is not mandatory to be used just after the declaration or may be the program requires the data to be updated according to what user inputs. Hence only declaration us also useful.
7. If constructor arguments are passed to objects of array then ____________ if the constructors are overloaded.
a) It is mandatory to pass same number of arguments to all the objects
b) It is mandatory to pass same type of arguments to all the objects
c) It is not mandatory to call same constructor for all the objects
d) It is mandatory to call same constructor for all the constructors
Explanation: It is not mandatory to call the same constructor for all the objects in an array if initialized with the declaration. The objects can be passed with different set of arguments in the same syntax, separated by commas.
8. How the objects of array can be denoted?
c) Random numbers
Explanation: Different objects in an array can be denoted with the indices of array. The first object is denoted by 0. And the further indices denote the next objects in sequence of array.
9. The objects in an object array _______________________
a) Can be created without use of constructor
b) Can be created without calling default constructor
c) Can’t be created with use of constructor
d) Can’t be created without calling default constructor
Explanation: The objects need some constructor to get the memory spaced reserved for those. If the default constructor is not used then we can use some arguments constructor which will reserve the memory for the objects. The objects can be passed with constructor arguments during declaration.
10. The Object array is created in _____________________
a) Heap memory
b) Stack memory
Explanation: If the object arrays are declared dynamically, then the memory will be reserved on heap. The memory for objects will be on stack only if some constructor or some call and return tasks are happening. The program doesn’t run on HDD and ROM is not used for the execution of programs.
11. If an array of objects is of size 10 and a data value have to be retrieved from 5th object then ________________ syntax should be used.
b) Data_Type Array_Name.data_variable_name;
Explanation: The array name with the index of fifth element is called, i.e. index 4. Then the dot operator is used to access the data member of that object. This Allows us to access the data members of all the objects in an object array.
12. Can we have two dimensional object array?
a) Yes, always
b) Yes, only if primitive type array
c) No, since two indices are impossible
d) No, never
Explanation: A two dimensional array can always be created. There is no rule that only primitive type objects can have more than one dimension. The object array can also be made 2 dimensional.
13. From which index does the array of objects start?
Explanation: The index must start from 0. The index ends at size – 1 index. This is because the index is always till n-1 where n is the total number of beads.
14. Two dimensional array can’t be initialized with the declaration.
Explanation: The two dimensional arrays can also be initialized using curly brackets. For each set, values in curly bracket. And then another bracket is added at first and end. This ensures that all the code belongs to the user.
15. Is an array of characters always a string?
a) Yes, always
b) Yes, if each character is terminated by null
c) No, since each character is terminated by null
d) No, never
Explanation: The character arrays are not the same as string. The string once created then remains the same. The character array values may change.
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