250+ TOP MCQs on References – 1 and Answers

This section on C++ interview questions and answers on “References”. One shall practice these interview questions to improve their C++ programming skills needed for various interviews (campus interviews, walk-in interviews, company interviews), placements, entrance exams and other competitive exams. These questions can be attempted by anyone focusing on learning C++ programming language. They can be a beginner, fresher, engineering graduate or an experienced IT professional. Our C++ interview questions come with the detailed explanation of the answers which helps in better understanding of C++ concepts.

Here is a listing of C++ interview questions on “References” along with answers, explanations and/or solutions:

1. Which value can we not assign to reference?
a) integer
b) floating
c) unsigned
d) null
Answer: d
Clarification: If it can be assigned with a null value means, it is a copy of the pointer.

2. Identify the incorrect statement.
a) Reference is the alternate name of the object
b) A reference value once defined can be reassigned
c) A reference value once defined cannot be reassigned
d) Reference is the alternate name of the variable
Answer: b
Clarification: Reference is a thing which points to the valid memory address, so it can’t be redesigned.

3. Which reference modifier is used to define the reference variable?
a) &
b) $
c) #
d) @
Answer: a
Clarification: & aka ‘ampersand’ used to define a reference variable.

4. What will be the output of the following C++ code?

```
    #include 
```
```
    using namespace std;
```
```
    void swap(int &a, int &b);
```
```
    int main()
```
```
    {
```
```
        int a = 5, b = 10;
```
```
        swap(a, b);
```
```
        cout << "In main " << a << b;
```
```
        return 0;
```
```
    }
```
```
    void swap(int &a, int &b)
```
```
    {
```
```
        int temp;
```
```
        temp = a;
```
```
        a = b;
```
```
        b = temp;
```
```
        cout << "In swap " << a << b;
```
```
    }
```

a) In swap 105 In main 105
b) In swap 105 In main 510
c) In swap 510 In main 105
d) In swap 510 In main 510
Answer: a
Clarification: As the function is called by reference i.e. all the changes are done directly into the memories of a and b. Therefore changes made to a and b in swap function is reflected back to main function. Hence the values of a and b in swap as well as in main function is changed.
Output:

$ g++ ref.cpp
$ a.out
In swap 105 In main 105

5. What does a reference provide?
a) Alternate name for the class
b) Alternate name for the variable
c) Alternate name for the pointer
d) Alternate name for the object
Answer: b
Clarification: Because we are pointing memory address using the temp variable.

6. What will be the output of the following C++ code?

```
    #include 
```
```
    using namespace std;
```
```
    int main()
```
```
    {
```
```
        int a = 9;
```
```
        int & aref = a;
```
```
        a++;
```

        cout << "The value of a is " << aref;

```
        return 0;
```
```
    }
```

a) 9
b) 10
c) error
d) 11
Answer: b
Clarification: The value is declared and it isincrementedrement, so it’s value is 10.

$ g++ ref1.cpp
$ a.out
10

a) Hello world
b) Hello
c) world
d) compile time error
Answer: a
Clarification: In this program we used the concept of constant casting to cast the variable and printing it.
Output:

250+ TOP MCQs on References – 1 and Answers

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