250+ TOP MCQs on Unions and Answers [2024]

C Objective Questions on “Unions”. One shall practice these Objective Questions to improve their C programming skills needed for various interviews (campus interviews, walkin 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 Objective Questions come with detailed explanation of the answers which helps in better understanding of C concepts.

Here is a listing of C Objective Questions on “Unions” along with answers, explanations and/or solutions:

1. What will be the output of the following C code?

```
    #include 
```
```
    union
```
```
    {
```
```
        int x;
```
```
        char y;
```
```
    }p;
```
```
    int main()
```
```
    {
```
```
        p.x = 10;
```
```
        printf("%dn", sizeof(p));
```
```
    }
```

a) Compile time error
b) sizeof(int) + sizeof(char)
c) Depends on the compiler
d) sizeof(int)
Answer: d
Clarification: None.

2. What will be the output of the following C code?

```
    #include 
```
```
    union
```
```
    {
```
```
        int x;
```
```
        char y;
```
```
    }p;
```
```
    int main()
```
```
    {
```
```
        p.y = 60;
```
```
        printf("%dn", sizeof(p));
```
```
    }
```

a) Compile time error
b) sizeof(int) + sizeof(char)
c) Depends on the compiler
d) sizeof(char)
Answer: c
Clarification: None.

3. What will be the output of the following C code?

```
    #include 
```
```
    union p
```
```
    {
```
```
        int x;
```
```
        char y;
```
```
    };
```
```
    int main()
```
```
    {
```
```
        union p p, b;
```
```
        p.y = 60;
```
```
        b.x = 12;
```
```
        printf("%dn", p.y);
```
```
    }
```

a) Compile time error
b) Depends on the compiler
c) 60
d) Undefined behaviour
Answer: c
Clarification: None.

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

```
    #include 
```
```
    union p
```
```
    {
```
```
        int x;
```
```
        char y;
```
```
    }k = {1, 97};
```
```
    int main()
```
```
    {
```
```
        printf("%dn", k.y);
```
```
    }
```

a) Compile time error
b) 97
c) a
d) 1
Answer: d
Clarification: None.

5. What will be the output of the following C code?

```
    #include 
```
```
    union p
```
```
    {
```
```
        int x;
```
```
        char y;
```
```
    }k = {.y = 97};
```
```
    int main()
```
```
    {
```
```
        printf("%dn", k.y);
```
```
    }
```

a) Compile time error
b) 97
c) a
d) Depends on the standard
Answer: b
Clarification: None.

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

```
    #include 
```
```
    union p
```
```
    {
```
```
        int x;
```
```
        float y;
```
```
    };
```
```
    int main()
```
```
    {
```
```
        union p p, b;
```
```
        p.x = 10;
```
```
        printf("%fn", p.y);
```
```
    }
```

a) Compile time error
b) Implementation dependent
c) 10.000000
d) 0.000000
Answer: b
Clarification: None.

7. Which of the following share a similarity in syntax?

1. Union, 2. Structure, 3. Arrays and 4. Pointers

a) 3 and 4
b) 1 and 2
c) 1 and 3
d) 1, 3 and 4
Answer: b
Clarification: None.

8. What will be the output of the following C code? (Assuming size of char = 1, int = 4, double = 8)

```
    #include 
```
```
    union utemp
```
```
    {
```
```
        int a;
```
```
        double b;
```
```
        char c;
```
```
    }u;
```
```
    int main()
```
```
    {
```
```
        u.c = 'A';
```
```
        u.a = 1;
```
```
        printf("%d", sizeof(u));
```
```
    }
```

a) 1
b) 4
c) 8
d) 13
Answer: c
Clarification: None.

Leave a Reply Cancel reply