250+ TOP MCQs on Bit-fields and Answers [2024]

C helps anyone preparing for LSI and other companies C interviews. One should practice these Objective Questions and answers continuously for 2-3 months to clear LSI interviews on C Programming language.

Here is a listing of C programming questions on “Bit-Fields” along with answers, explanations and/or solutions:

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

```
    #include 
```
```
    struct p
```
```
    {
```
```
        char x : 2;
```
```
        int y : 2;
```
```
    };
```
```
    int main()
```
```
    {
```
```
        struct p p;
```
```
        p.x = 2;
```
```
        p.y = 1;
```
```
        p.x = p.x & p.y;
```
```
        printf("%dn", p.x);
```
```
    }
```

a) 0
b) Compile time error
c) Undefined behaviour
d) Depends on the standard
Answer: a
Clarification: None.

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

```
    #include 
```
```
    union u
```
```
    {
```
```
        struct p
```
```
        {
```
```
            unsigned char x : 2;
```
```
            unsigned int y : 2;
```
```
        };
```
```
        int x;
```
```
    };
```
```
    int main()
```
```
    {
```
```
        union u u;
```
```
        u.p.x = 2;
```
```
        printf("%dn", u.p.x);
```
```
    }
```

a) Compile time error
b) Undefined behaviour
c) Depends on the standard
d) 2
Answer: a
Clarification: None.

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

```
    #include 
```
```
    union u
```
```
    {
```
```
        struct
```
```
        {
```
```
            unsigned char x : 2;
```
```
            unsigned int y : 2;
```
```
        }p;
```
```
        int x;
```
```
    };
```
```
    int main()
```
```
    {
```
```
        union u u;
```
```
        u.p.x = 2;
```
```
        printf("%dn", u.p.x);
```
```
    }
```

a) Compile time error
b) 2
c) Undefined behaviour
d) Depends on the standard
Answer: b
Clarification: None.

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

```
    #include 
```
```
    union u
```
```
    {
```
```
        struct
```
```
        {
```
```
            unsigned char x : 2;
```
```
            unsigned int y : 2;
```
```
        }p;
```
```
        int x;
```
```
    };
```
```
    int main()
```
```
    {
```
```
        union u u.p.x = 2;
```
```
        printf("%dn", u.p.x);
```
```
    }
```

a) Compile time error
b) 2
c) Depends on the compiler
d) Depends on the standard
Answer: a
Clarification: None.

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

```
    #include 
```
```
    union u
```
```
    {
```
```
        struct
```
```
        {
```
```
            unsigned char x : 2;
```
```
            unsigned int y : 2;
```
```
        }p;
```
```
        int x;
```
```
    };
```
```
    int main()
```
```
    {
```
```
        union u u = {2};
```
```
        printf("%dn", u.p.x);
```
```
    }
```

a) Compile time error
b) 2
c) Depends on the standard
d) None of the mentioned
Answer: b
Clarification: None.

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

```
    #include 
```
```
    union u
```
```
    {
```
```
        struct
```
```
        {
```
```
            unsigned char x : 2;
```
```
            unsigned int y : 2;
```
```
        }p;
```
```
        int x;
```
```
    };
```
```
    int main()
```
```
    {
```
```
        union u u.p = {2};
```
```
        printf("%dn", u.p.x);
```
```
    }
```

a) Compile time error
b) 2
c) Undefined behaviour
d) None of the mentioned
Answer: a
Clarification: None.

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

```
    #include 
```
```
    struct p
```
```
    {
```
```
        unsigned int x : 2;
```
```
        unsigned int y : 2;
```
```
    };
```
```
    int main()
```
```
    {
```
```
        struct p p;
```
```
        p.x = 3;
```
```
        p.y = 1;
```
```
        printf("%dn", sizeof(p));
```
```
    }
```

a) Compile time error
b) Depends on the compiler
c) 2
d) 4
Answer: d
Clarification: None.

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

```
    #include 
```
```
    struct p
```
```
    {
```
```
        unsigned int x : 2;
```
```
        unsigned int y : 2;
```
```
    };
```
```
    int main()
```
```
    {
```
```
        struct p p;
```
```
        p.x = 3;
```
```
        p.y = 4;
```
```
        printf("%dn", p.y);
```
```
    }
```

a) 0
b) 4
c) Depends on the compiler
d) 2
Answer: a
Clarification: None.

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

```
    #include 
```
```
    struct p
```
```
    {
```
```
        unsigned int x : 7;
```
```
        unsigned int y : 2;
```
```
    };
```
```
    int main()
```
```
    {
```
```
        struct p p;
```
```
        p.x = 110;
```
```
        p.y = 2;
```
```
        printf("%dn", p.x);
```
```
    }
```

a) Compile time error
b) 110
c) Depends on the standard
d) None of the mentioned
Answer: b
Clarification: None.

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

```
    #include 
```
```
    struct p
```
```
    {
```
```
        unsigned int x : 1;
```
```
        unsigned int y : 1;
```
```
    };
```
```
    int main()
```
```
    {
```
```
        struct p p;
```
```
        p.x = 1;
```
```
        p.y = 2;
```
```
        printf("%dn", p.y);
```
```
    }
```

a) 1
b) 2
c) 0
d) Depends on the compiler
Answer: c
Clarification: None.

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