20 Lecture
CS304
Midterm & Final Term Short Notes
SUBSCRIPT [] OPERATOR
The subscript operator [] is used to access elements of an array or elements of a container class such as a vector or a map. It can be overloaded for user-defined classes to provide custom element access behavior. The overloaded operator functio
Important Mcq's
Midterm & Finalterm Prepration
Past papers included
Download PDF
- Which operator is used to access elements of an array or container class?
a) () operator
b) {} operator
c) [] operator
d) -> operator
Answer: c) [] operator
What is the parameter type for an overloaded subscript operator function?
a) int
b) char
c) string
d) Depends on the type of the elements being accessed
Answer: d) Depends on the type of the elements being accessed
Which of the following is a valid use of the subscript operator?
a) accessing the nth character of a string
b) accessing the nth element of an array
c) accessing the nth element of a vector
d) all of the above
Answer: d) all of the above
What is the return type of the subscript operator function?
a) void
b) int
c) char
d) Depends on the type of the elements being accessed
Answer: d) Depends on the type of the elements being accessed
Which of the following is true regarding the subscript operator overloading?
a) Only one overload of the subscript operator is allowed per class.
b) The overload function must be a member function of the class.
c) The overload function must be a friend function of the class.
d) The overload function must take two parameters.
Answer: b) The overload function must be a member function of the class.
What is the purpose of subscript operator overloading?
a) To provide a custom element access behavior for user-defined classes.
b) To access private data members of a class.
c) To perform arithmetic operations on array elements.
d) None of the above.
Answer: a) To provide a custom element access behavior for user-defined classes.
Which of the following is a disadvantage of using the subscript operator?
a) It can lead to out-of-bounds access.
b) It is slower than pointer arithmetic.
c) It cannot be used with containers like maps and sets.
d) It cannot be overloaded for user-defined classes.
Answer: a) It can lead to out-of-bounds access.
Which of the following is true regarding the subscript operator overloading for a container class?
a) The operator function must return a reference to the element being accessed.
b) The operator function must return a copy of the element being accessed.
c) The operator function must take a single parameter of type int.
d) The operator function is not allowed to modify the container.
Answer: a) The operator function must return a reference to the element being accessed.
Which of the following is a valid example of subscript operator overloading?
a) int operator[](int i);
b) void operator[](int i);
c) int& operator[](int i);
d) int* operator[](int i);
Answer: c) int& operator[](int i);
What happens if the subscript operator function returns a copy of the element being accessed?
a) The copy is returned by value and can be modified independently of the original element.
b) The copy is returned by reference and any modifications made to it will affect the original element.
c) The program will not compile.
d) None of the above.
Answer: a) The copy is returned by value and can be modified independently of the original element.
Subjective Short Notes
Midterm & Finalterm Prepration
Past papers included
Download PDF
- What is the purpose of the subscript operator in C++?
The subscript operator is used to access individual elements of an array or objects that support subscripting.
How is the subscript operator implemented in a class?
The subscript operator can be overloaded in a class by defining a method that takes an integer index as a parameter and returns a reference to the object at that index.
Can the subscript operator be overloaded for non-integer types?
Yes, the subscript operator can be overloaded for any type that can be used as an index, including non-integer types such as strings or custom classes.
How does the subscript operator differ from a regular function call?
The subscript operator is used with square brackets [] and is used to access a specific element of an array or object, whereas a regular function call is used to execute a specific function and can take any number of parameters.
Can the subscript operator be used for both reading and writing data?
Yes, the subscript operator can be overloaded to allow both reading and writing of data.
What is the return type of the subscript operator method?
The return type of the subscript operator method is typically a reference to the object type of the array or collection being indexed.
How can the subscript operator be used with pointers?
The subscript operator can be used with pointers by first dereferencing the pointer and then using the subscript operator on the resulting object.
What happens if an index is out of bounds when using the subscript operator?
If an index is out of bounds when using the subscript operator, the behavior is undefined and may result in a segmentation fault or other runtime error.
How does the subscript operator work with multidimensional arrays?
The subscript operator can be overloaded to support multidimensional arrays by taking multiple indices as parameters and returning a reference to the object at that location.
Can the subscript operator be used with standard library containers?
Yes, many standard library containers in C++ support the subscript operator, including vectors, arrays, and maps.
In C++, the Subscript [] operator is used to provide the ability to access individual elements of an array-like object or a custom container class by using an index value. The operator can be overloaded to support custom types and classes that can be indexed.
To overload the subscript [] operator, we define a member function within the class definition that takes an integer argument and returns a reference to the element at that index. The syntax of the overloaded operator is as follows:
The operator function must be declared as a member function of the class, and it should return a reference to the element at the specified index. This allows us to both read and modify the elements of the object by using the subscript operator.
For example, suppose we have a class named
This allows us to access the elements of the
In this way, the Subscript [] operator can make it more convenient to work with custom container classes and array-like objects, providing a more natural and intuitive syntax for accessing their elements.
perl
T& operator[](int index) {
// return element at index
}
MyArray that represents an array of integers. We can overload the subscript [] operator to provide access to the elements of the array as follows:
arduino
class MyArray {
private:
int arr[10];
public:
int& operator[](int index) {
return arr[index];
}
};
MyArray object by using the subscript [] operator, like this:
less
MyArray arr;
arr[0] = 1; // set the first element to 1
int x = arr[0]; // get the value of the first element