Union in C Language - Quiz

Q: What is the output of this C code?

    #include "stdio.h"
    struct
    {
        char *name;
        union
        {
            char *sval;
        } u;
    } symtab[10];

the first character of the string sval by either of

A. *symtab[i].u.sval
B. symtab[i].u.sval[0].
C. You cannot have union inside structure
D. Both *symtab[i].u.sval & symtab[i].u.sval[0].

Correct Option: D
Remarks:

Explanation: Both *symtab[i].u.sval & symtab[i].u.sval[0].

Q: What will be the output of the program?

#include"stdio.h"

int main()
{
    union a
    {
        int i;
        char ch[2];
    };
    union a u;
    u.ch[0]=3;
    u.ch[1]=2;
    printf("%d, %d, %d\n", u.ch[0], u.ch[1], u.i);
    return 0;
}

A. 3, 2, 515
B. 515, 2, 3
C. 3, 2, 5
D. 515, 515, 4

Correct Option: A
Remarks:

Explanation: Option A

Q: What will be the output of the program?

#include"stdio.h"

int main()
{
    struct value
    {
        int bit1:1;
        int bit3:4;
        int bit4:4;
    }bit={1, 2, 13};

    printf("%d, %d, %d\n", bit.bit1, bit.bit3, bit.bit4);
    return 0;
}

A. 1, 2, 13
B. 1, 4, 4
C. -1, 2, -3
D. -1, -2, -13

Correct Option: C
Remarks:

Explanation:

Note the below statement inside the struct:

int bit1:1; --> 'int' indicates that it is a SIGNED integer.

For signed integers the leftmost bit will be taken for +/- sign.

If you store 1 in 1-bit field:

The left most bit is 1, so the system will treat the value as negative number.

The 2's complement method is used by the system to handle the negative values.

Therefore, the data stored is 1. The 2's complement of 1 is also 1 (negative).

Therefore -1 is printed.

If you store 2 in 4-bits field:

Binary 2: 0010 (left most bit is 0, so system will treat it as positive value)

0010 is 2

Therefore 2 is printed.

If you store 13 in 4-bits field:

Binary 13: 1101 (left most bit is 1, so system will treat it as negative value)

Find 2's complement of 1101:

1's complement of 1101 : 0010
2's complement of 1101 : 0011 (Add 1 to the result of 1's complement)

0011 is 3 (but negative value)

Therefore -3 is printed.

Q: What will be the output of the program?


#include<stdio.h>

int main()
{
    enum status {pass, fail, absent};
    enum status stud1, stud2, stud3;
    stud1 = pass;
    stud2 = absent;
    stud3 = fail;
    printf("%d %d %d\n", stud1, stud2, stud3);
    return 0;
}

A. 0, 1, 2
B. 1, 2, 3
C. 0, 2, 1
D. 1, 3, 2

Correct Option: C
Remarks:

Explanation: 0, 2, 1

Q: What will be the output of the program?


#include<stdio.h>

int main()
{
    struct byte
    {
        int one:1;
    };
    struct byte var = {1};
    printf("%d\n", var.one);
    return 0;
}

A. 1
B. -1
D. Error

Correct Option: B
Remarks:

Explanation: -1

Q: What will be the output of the program?


#include<stdio.h>

    struct course
    {
        int courseno;
        char coursename[25];
    };
int main()
{
    struct course c[] = { {102, "Java"}, 
                          {103, "PHP"}, 
                          {104, "DotNet"}     };

    printf("%d ", c[1].courseno);
    printf("%s\n", (*(c+2)).coursename);
    return 0;
}

A. 103 DotNet
B. 102 Java
C. 103 PHP
D. 104 DotNet

Correct Option: A
Remarks:

Explanation: 103 DotNet

Q: What is the output of this C code?


    #include <stdio.h>
    union
    {
        int x;
        char y;
    }p;
    int main()
    {
        p.y = 60;
        printf("%d\n", sizeof(p));
    }

A. Compile time error
B. sizeof(int) + sizeof(char)
C. Depends on the compiler
D. sizeof(char)

Correct Option: C
Remarks:

Explanation: Depends on the compiler

Q: What is the output of this C code?


    #include <stdio.h>
    union p
    {
        int x;
        char y;
    };
    int main()
    {
        union p p, b;
        p.y = 60;
        b.x = 12;
        printf("%d\n", p.y);
    }

A. Compile time error
B. Depends on the compiler
C. 60
D. Undefined behaviour

Correct Option: C
Remarks:

Explanation: 60

Q: What is the output of this C code?


    #include <stdio.h>
    union p
    {
        int x;
        float y;
    };
    int main()
    {
        union p p, b;
        p.x = 10;
        printf("%f\n", p.y);
    }

A. Compile time error
B. Implementation dependent
C. 10.000000
D. 0.000000

Correct Option: B
Remarks:

Explanation: Implementation dependent

Q: 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

Correct Option: B
Remarks:

Explanation: 1 and 2

Union in C Language - Quiz

What is the output of this C code?
#include "stdio.h" struct { char name; union { char sval; } u; } symtab[10];
the first character of the string sval by either of

What will be the output of the program?
#include"stdio.h" int main() { union a { int i; char ch[2]; }; union a u; u.ch[0]=3; u.ch[1]=2; printf("%d, %d, %d\n", u.ch[0], u.ch[1], u.i); return 0; }

What will be the output of the program?
#include"stdio.h" int main() { struct value { int bit1:1; int bit3:4; int bit4:4; }bit={1, 2, 13}; printf("%d, %d, %d\n", bit.bit1, bit.bit3, bit.bit4); return 0; }

What will be the output of the program?

What will be the output of the program?

What will be the output of the program?

What is the output of this C code?

What is the output of this C code?

What is the output of this C code?

Which of the following share a similarity in syntax?
1. Union, 2. Structure, 3. Arrays and 4. Pointers

Union in C Language - Quiz

What is the output of this C code? #include "stdio.h" struct { char *name; union { char *sval; } u; } symtab[10]; the first character of the string sval by either of

What will be the output of the program? #include"stdio.h" int main() { union a { int i; char ch[2]; }; union a u; u.ch[0]=3; u.ch[1]=2; printf("%d, %d, %d\n", u.ch[0], u.ch[1], u.i); return 0; }

What will be the output of the program? #include"stdio.h" int main() { struct value { int bit1:1; int bit3:4; int bit4:4; }bit={1, 2, 13}; printf("%d, %d, %d\n", bit.bit1, bit.bit3, bit.bit4); return 0; }

What will be the output of the program? #include<stdio.h> int main() { enum status {pass, fail, absent}; enum status stud1, stud2, stud3; stud1 = pass; stud2 = absent; stud3 = fail; printf("%d %d %d\n", stud1, stud2, stud3); return 0; }

What will be the output of the program? #include<stdio.h> int main() { struct byte { int one:1; }; struct byte var = {1}; printf("%d\n", var.one); return 0; }

What will be the output of the program? #include<stdio.h> struct course { int courseno; char coursename[25]; }; int main() { struct course c[] = { {102, "Java"}, {103, "PHP"}, {104, "DotNet"} }; printf("%d ", c[1].courseno); printf("%s\n", (*(c+2)).coursename); return 0; }

What is the output of this C code? #include <stdio.h> union { int x; char y; }p; int main() { p.y = 60; printf("%d\n", sizeof(p)); }

What is the output of this C code? #include <stdio.h> union p { int x; char y; }; int main() { union p p, b; p.y = 60; b.x = 12; printf("%d\n", p.y); }

What is the output of this C code? #include <stdio.h> union p { int x; float y; }; int main() { union p p, b; p.x = 10; printf("%f\n", p.y); }

Which of the following share a similarity in syntax? 1. Union, 2. Structure, 3. Arrays and 4. Pointers

What is the output of this C code?
#include "stdio.h" struct { char name; union { char sval; } u; } symtab[10];
the first character of the string sval by either of

What will be the output of the program?
#include"stdio.h" int main() { union a { int i; char ch[2]; }; union a u; u.ch[0]=3; u.ch[1]=2; printf("%d, %d, %d\n", u.ch[0], u.ch[1], u.i); return 0; }

What will be the output of the program?
#include"stdio.h" int main() { struct value { int bit1:1; int bit3:4; int bit4:4; }bit={1, 2, 13}; printf("%d, %d, %d\n", bit.bit1, bit.bit3, bit.bit4); return 0; }

What will be the output of the program?

What will be the output of the program?

What will be the output of the program?

What is the output of this C code?

What is the output of this C code?

What is the output of this C code?

Which of the following share a similarity in syntax?
1. Union, 2. Structure, 3. Arrays and 4. Pointers