Structure questions with explanation in c


Structure in c example

(q) What will be output of following c code?

void main()
{
struct employee
{
unsigned id: 8;
unsigned sex:1;
unsigned age:7;
};
struct employee emp1={203,1,23};
clrscr();
printf("%d\t%d\t%d",emp1.id,emp1.sex,emp1.age);
getch();
}

Output: 203 1 23
We can access the data member in same way.
How bit data is stored in the memory:

Minimum size of structure which data member in bit is two byte i.e. 16 bit. This is called word size of microprocessor. Word size depends on microprocessor. Turbo c is based on 8086 microprocessor which word size is two byte.


Bits are filed in from right to left direction 8 bit for id,1 bit for sex and 7 bit for age.

(q) What will be output of following c code?

void main()
{
struct bitfield
{
unsigned a:5;
unsigned c:5;
unsigned b:6;

}bit;
char *p;
struct bitfield *ptr,bit1={1,3,3};
p=&bit1;
p++;
clrscr();
printf("%d",*p);
getch();
}

Output: 12
Explanation:
Binary value of a=1 is 00001 (in 5 bit)
Binary value of b=3 is 00011 (in 5 bit)
Binary value of c=3 is 000011 (in 6 bit)
In memory it is represented as:


Let address of bit1 is 500 which initialize to char pointer p. Since can is one byte data type so p++ will be 501. *p means content of memory location 501 which is (00001100) and its binary equivalent is 12. Hence output is 12.

(q) What will be output of following c code?

void main()
{
struct bitfield
{
signed int a:3;
unsigned int b:13;
unsigned int c:1;
};
struct bitfield bit1={2,14,1};
clrscr();
printf("%d",sizeof(bit1));
getch();
}

Output: 4
(q) What will be output of following c code?

void main()
{
struct bitfield
{
unsigned a:3;
char b;
unsigned c:5;
int d;
}bit;
clrscr();
printf("%d",sizeof(bit));
getch();
}

Output: 5

Note: (Actual output will 6 due to slack byte ,So Before executing this program first go to option menu then compiler then code generation then select word alignment then press OK)

(q) What will be output of following c code?
void main()
{
struct field
{
int a;
char b;
}bit;
struct field bit1={5,'A'};
char *p=&bit1;
*p=45;
clrscr();
printf("\n%d",bit1.a);
getch();
}

Output: 45
Nesting of structure:

Nesting of structure is possible i.e. we can declare a structure within another structure but it is necessary inner structure must declares structure variable otherwise we can not access the data member of inner structure.
Example:

void main()
{
struct world
{
int a;
char b;
struct india
{
char c;
float d;
}p;
};
struct world st ={1,'A','i',1.8};
clrscr();
printf("%d\t%c\t%c\t%f",st.a,st.b,st.p.c,st.p.d);
getch();
}

Output: 1 A I 1.800000

(q) What will be output of following c code?

void main()
{
struct india
{
char c;
float d;
};
struct world
{
int a[3];
char b;
struct india orissa;
};
struct world st ={{1,2,3},'P','q',1.4};
clrscr();
printf("%d\t%c\t%c\t%f",st.a[1],st.b,st.orissa.c,st.orissa.d);
getch();
}

Output: 2 p q 1.400000

23 comments:

  1. the answer to the third question is coming out to be 3 in borland C 4.5
    and individually the size of signed and unsigned int is coming to be 2 each
    wat is the correct ans....m getting confused

    ReplyDelete
  2. I also do not follow the 3 question. I compiled it on the gcc compiler(linux) and the answer I got was 4. I think it is some thing to do with slack memory

    ReplyDelete
  3. As you know c is compiler dependent. Size of data type varies from compiler to compiler. Output of above program will be accordingly. Answer of above
    questions is only valid to that compiler with world size is two byte. If you are using other compiler then try to adjust accordingly. Please didn't confused.

    ReplyDelete
  4. please include web designing tutorial

    ReplyDelete
  5. C is compiler dependent as we all know.So if u try the 5th question in borland c you will get the answer 5 where as in visual studio you will find an answer of 16.So dnt get confuse with that concepts.

    ReplyDelete
  6. file pointer is a pointer to a structure of ________ type.

    ReplyDelete
  7. hi please explay any one question number two brifely

    ReplyDelete
  8. please give the answer for the 3 question

    ReplyDelete
  9. how to write a program to find grade of student

    ReplyDelete
  10. Plz tell me if there hav any secret method or easier technique for coding in C using RECURSION...

    ReplyDelete
  11. Hi Harekrushna,

    Good questions. Go through the following link:
    http://cquestionbank.blogspot.com/2009/06/function-recursion-in-c-programming.html

    ReplyDelete
  12. excelent questions and it will be more help to me but i think we need more explanation
    PRASAD and NARESH

    ReplyDelete
  13. #include
    #include

    struct std{
    int roll;
    void f(){
    struct std x;
    roll =7;
    printf("%d",roll);
    };

    void main(){
    struct std x;
    x.f();
    }
    "THIS PROGRAM CAN NOT RUN COMPILATION ERROR AND THE IS decleration terminate
    incorrectly" plz help me...

    ReplyDelete
    Replies
    1. in c language you can not define a function inside the structure.to overcome such limitation class concept came in C++.
      Hope you find it useful :)

      Delete
  14. saurabh gupta7/18/12, 11:27 AM

    how the answer for 5th questin is 5??

    shudn't it be 7??

    ReplyDelete
  15. Hi All,
    can anyone tell me why the o/p of below code is 20 under gcc..

    struct abc {
    char name[10];
    int i;
    char val;
    };
    int main(){
    printf("%d\n",sizeof(struct abc));
    }

    ReplyDelete
  16. PLZ ANS THIS--enter the basic salary of employe calculate the following-
    1)per day salary
    2)weekly salary
    3)annual salary
    4)calculate houserent 15% of basic salary
    5)caculate medical 10%of basic salary
    6)caculate da 30% of baic salary
    7)calculate ta 10% of basic salary
    8)calculate pf 12% of basic salary
    9) calculate gross salary
    10)calculate net salary

    ReplyDelete
  17. Hi Please explain in brief about the allignment of data types in structure? How can we do structure padding with an example. it would be very confusing for me ...

    ReplyDelete
  18. Hi ritsh kumar, i got error in some programs in structure with pointer program section of ur tutorial. So check and correct that.

    ReplyDelete
  19. Nice collection..

    ReplyDelete
  20. please include ethical hacking tutorial hacking tutorials

    ReplyDelete