C++ Interview Questions Answers - Sizes

This section on C++ interview questions and answers focuses on “Sizes”. 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 “Sizes” along with answers, explanations and/or solutions:

1. The size of an object or a type can be determined using which operator?
a) malloc
b) sizeof
c) malloc
d) calloc
View Answer

Answer: b
Explanation: The sizeof operator gives the size of the object or type.

2. It is guaranteed that a ____ has at least 8 bits and a ____ has at least 16 bits.
a) int, float
b) char, int
c) bool, char
d) char, short
View Answer

Answer: d
Explanation: char types in C++ require atleast 8 bits and short requires atleast 16 bits, whereas for bool only 1 bit suffices and both int and float requires atleast 32 bits.

3. Implementation dependent aspects about an implementation can be found in ____
a) <implementation>
b) <limits>
c) <limit>
d) <numeric>
View Answer

Answer: b
Explanation: The limit header holds the details of the machine dependent details.

4. Size of C++ objects are expressed in terms of multiples of the size of a ____ and the size of a char is _______
a) char, 1
b) int, 1
c) float, 8
d) char, 4
View Answer

Answer: a
Explanation: Each object in C++ is expressed in terms of char type and size of char type is one byte.

5. Identify the incorrect option.
a) 1 <= sizeof(bool) <= sizeof(long)
b) sizeof(float) <= sizeof(double) <= sizeof(long double)
c) sizeof(char) <= sizeof(long) <=sizeof(wchar_t)
d) sizeof(N) = sizeof(signed N) = sizeof(unsigned N)
View Answer

Answer: c
Explanation: sizeof(char) <= sizeof(wchar_t) <= sizeof(long).

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

```
    #include <iostream>
```
```
    using namespace std;
```
```
    int main()
```
```
    {
```
```
        int num = 0x20 + 020 + 20;
```
```
        cout << sizeof(num)<<'\n';
```
```
        return 0;
```
```
    }
```

a) 2
b) 4
c) Depends on compiler
d) Garbage
View Answer

Answer: c
Explanation: The sum of three numbers are belongs to different number systems, so the result is type casted into integer.
Output:

$ g++ size.cpp
$ a.out
4

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

```
    #include <iostream>
```
```
    using namespace std;
```
```
    int main ( )
```
```
    {
```
```
        static double i;
```
```
        i = 20;
```
```
        cout << sizeof(i);
```
```
        return 0;
```
```
    }
```

a) 4
b) 2
c) 8
d) garbage
View Answer

Answer: c
Explanation: The size of the double data type is 8.

$ g++ size1.cpp
$ a.out
8

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

```
    #include <iostream>
```
```
    using namespace std;
```
```
    int main()
```
```
    {
```
```
        int num1 = 10;
```
```
        float num2 = 20;
```
```
        cout << sizeof(num1 + num2);
```
```
        return 0;
```
```
    }
```

a) 2
b) 4
c) 8
d) garbage
View Answer

Answer: b
Explanation: In this program, integer is converted into float. Therefore the result of num1 and num2 is float. And it is returning the size of the float.
Output:

$ g++ size2.cpp
$ a.out
4

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

```
    #include <iostream>
```
```
    using namespace std;
```
```
    int main()
```
```
    {
```
```
        int a = 5;
```
```
        float b;
```
```
        cout << sizeof(++a + b);
```
```
        cout << a;
```
```
        return 0;
```
```
    }
```

a) 2 6
b) 4 6
c) 2 5
d) 4 5
View Answer

Answer: d
Explanation: The a as a integer will be converted to float while calculating the size. The value of any variable doesn’t modify inside sizeof operator. Hence value of variable a will remain 5.
Output: