Output of C programs | Set 44 (Structure & Union)

Prerequisite: Structure and Union
QUE.1 What is the output of this program? 

#include <stdio.h>
struct sample {
    int a = 0;
    char b = 'A';
    float c = 10.5;
};
int main()
{
    struct sample s;
    printf("%d, %c, %f", s.a, s.b, s.c);
    return 0;
}

OPTION 
a) Error 
b) 0, A, 10.5 
c) 0, A, 10.500000 
d) No Error, No Output 

Answer: a

Explanation: Error: Can not initialize members here. We can only declare members inside the structure, initialization of member with declaration is not allowed in structure declaration.
QUE.2 What is the output of this program? 

#include <stdio.h>
int main()
{
    struct bitfield {
        signed int a : 3;
        unsigned int b : 13;
        unsigned int c : 1;
    };
    struct bitfield bit1 = { 2, 14, 1 };
    printf("%ld", sizeof(bit1));
    return 0;
}

OPTION 
a) 4 
b) 6 
c) 8 
d) 12 

Answer:  a

Explanation: struct bitfield bit1={2, 14, 1}; when we initialize it, it will take only one value that will be int and size of int is 4
QUE. 3 What is the output of this program? 

#include <stdio.h>
int main()
{
    typedef struct tag {
        char str[10];
        int a;
    } har;

    har h1, h2 = { "IHelp", 10 };
    h1 = h2;
    h1.str[1] = 'h';
    printf("%s, %d", h1.str, h1.a);
    return 0;
}

OPTION 
a) ERROR 
b) IHelp, 10 
c) IHelp, 0 
d) Ihelp, 10 

Answer : d

Explanation: It is possible to copy one structure variable into another like h1 = h2. Hence value of h2. str is assigned to h1.str.
QUE.4 What is the output? 

#include <stdio.h>

struct sample {
    int a;
} sample;

int main()
{
    sample.a = 100;
    printf("%d", sample.a);
    return 0;
}

OPTION 
a) 0 
b) 100 
c) ERROR 
d) Warning 
Answer 

Answer : b

Explanation : This type of declaration is allowed in c.
QUE.5 what is output of this program? 

#include <stdio.h>
int main()
{
    union test {
        int i;
        int j;
    };

    union test var = 10;
    printf("%d, %d\n", var.i, var.j);
}

OPTION 
a) 10, 10 
b) 10, 0 
c) 0, 10 
d) Compile Error

Answer : d

Explanation : Error: Invalid Initialization. You cannot initialize an union variable like this.
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