Technical Interview Questions and Answers :: C

For loop is used when we know how many times

to check if the ith bit is on or off in a number n following  bitwise operation is used.

flag = n&(1<<i) ;

if the value of flag is zero then the bit is set otherwise not.
explanation of above approach is as follows.

1. lets assume n is 9 so its bitwise operator is 1001 and bitwise representation of 1 is 0001

2.to check if 4th bit is on we do left shift by 4 on 1 (1<<4) which shift the bits in one to left by 4 unit now the (1<<4)=1000

3.Finally bitwise and operation is performed so  1001&1000 = 1000 which is not zero so it means that 4th bit of  9 is set

The bitwise operator xor i.e '^' is used to turn off a particular number

by performing the following operations say we want to turn the ith bit off in a number n

then n = n^(1<<i)

multiplying a number by two is equivalent to bitwise left shift of a number by 1 for eg

1 has a binary representation as 00001 left shift by 1 will make it 00010 which is 2.

right shift is equivalent to divide a number by 2 .

left shift is equivalent to multiply a number by 2.

Enumarations are list of integer constants, by default value is zero.

Structure is a function which contains different types of data types and allocation different memory location.

Structure- It is an user defined data function that allow to store multiple type of data in a single unit.

It occupies sum of memory of all location.

Whereas, Union- It is also an user defined data function that allow to store multiple type of data in a single unit.

But it occupies memory of largest member only. 

1.memory.

2.easy to declare.

Struct stack

{

#include<stdio.h>

struct name{

int a;

int b;

int c;

};

struct name func(){

    struct name s1 ;

s1.a=1;

s1.b=2;

s1.c=3;

return s1;

}

int main(){

    struct name val = func();

}