C programming Interview questions and answers: c language questions and answers

1. What will be the output if you will execute following c code?

#include<stdio.h>

int main(){

int xyz=1000;

int *ptr=&xyz;

printf("%d %d",++xyz,(*(int *)xyz)--);

return 0;

}

(A)	1000 999
(B)	1001 1000
(C)	1000 1000
(D)	999 999
(E)	Compilation error

Explanation:

Explanation:

printf function follows cedecl parameter passing convention. That is parameter will pass from right to left direction.

(*(int *)ptr)—-

= (*&val)—

= val—-

Here –- post decrement operator. So first it will assign its value i.e. printf function will print 1234 and value of variable val will decrement by one. So

val = 1233

Now second parameter will pass:

++val

So, val = 1234

What will be the output if you will execute following c code?

#include<stdio.h>

int main(){

int a=0;

for(a;++a;a<=100)

printf("%d",a);

return 0;

}

(A)	Print 1 to 99 infinite times
(B)	Print 1 to 99
(C)	Print some garbage values
(D)	Infinite loop
(E)	It will print 1 to MAX_INT then MIN_INT to -1

Explanation:

Consider on for loop:

Initial value: a

It will not affect any thing in the program.

Checking condition: ++a

It is incrementing the value of a by one in each iteration.

As we know in c zero means false. So when value of a will be zero loop will terminate.

Increment value: a <= 100

It is not incrementing the value of variable a.

So, it is clear loop will terminate when value of variable a will be zero. Hence printf function will print:

1 to 32765 then -32765 to -1 due to cyclic property of int

What will be the output if you will execute following c code?

#include<stdio.h>

int main(){

char c[6+4]="kill me";

printf("2%s",c);

return 0;

}

Explanation:

Here c is array of characters. It will store characters in the following manner:

In the printf function variable c will return memory address of first character ‘k’ i.e. 100. As we know %s will prints the stream of characters until it gets first null character (‘\0’).

What will be the output if you will execute following c code?

#include<stdio.h>

int main() {

int i=0;

for(;i++;printf("%d",i)) ;

printf("%d",i);

return 0;

}

What will be the output if you will execute following c code?

#include<stdio.h>

int main(){

int i,j=6;

for(;i=j;j-=2)

printf("%d",j);

return 0;

}

(A)	Compilation error
(B)	Garbage values
(C)	642
(D)	6420
(E)	Infinite loop

Explanation:

Initially:

I= Garbage

J= 6

In first iteration:

i= j = 6 i.e. condition is true.

It will print 6

J = j – 2 = 4

In second iteration:

I= j= 4 i.e. condition is true.

It will print 4

J = j – 2 = 2

In third iteration:

i= j = 2 i.e. condition is true.

It will print 2

J = j – 2 = 0

In fourth iteration:

i= j = 0 i.e. condition is false.

Hence program control will come out of the for loop.

State the correct statement.

I . In a while loop the control conditional check is performed n times.

II . In a do-while loop the control conditional check is performed n+1 times.

III . break is a keyword used with if and switch case.

What will be the output if you will execute following c code?

#include<stdio.h>

int main() {

printf("5","%f",4);

return 0;

}

What happens when if will write the value in array subscript operator which is beyond the size of array?

The order of evaluation of operators having same precedence is decided by

10.

The set of routines stored in ROM that enable a computer to start the O.S and to communicate with the various devices in the system is known as

11.

What will be the output if you will execute following c code?

#include<stdio.h>

struct main {

int n;

int (*p)();

};

int main() {

struct main m;

int fun();

m.n=fun();

m.p=fun;

(*(m.p))();

printf("%d",m.n);

return 0;

}

int fun() {

return printf("Hello");

}

(A)	Hello
(B)	HelloHello
(C)	HelloHello5
(D)	No output
(E)	Compilation error

Explanation:

m.n=fun();

Printf function always returns an integer value which is equal to number of characters it prints. So function fun will return 5 since “Hello” has five characters.

Structure main member variable p is pointer to such function which return type is int and parameter is int.

In the statement

m.p=fun;

Pointer p is pointing to function fun. So

(*(m.p))()

=(*&fun)()

=fun() //Since * and & always cancel to each other.

12.

What will be the output if you will execute following c code?

#include<stdio.h>

union spc {

int x;

int a:8;

char b:3;

};

int main() {

union spc s={260};

printf("%d %d", s.a,s.b);

return 0;

}

(A)	260 0
(B)	4 -4
(C)	4 4
(D)	260 4
(E)	Compilation error

Explanation:

Size of any union is size of maximum size of its any member variable.

x: it size is two byte or 16 bit

a: It size is 8 bit

b: Its size is 3 bit

So size of union spc is max (16, 8, 3) i.e. 16 bit or 2 byte.

Binary value of 260 is: 00000001 00000100

int data type (s.x=260)is stored in the following manner:

Consider on the union member variable a:

Data bit size: 7

Sign bit size: 1

Since a = 00000100 (In binary)

Data bit: 0000100

Sign bit: 0 (Zero means positive number)

Hence its equivalent decimal value is:

(-0) *2^7 + 0*2^6 + 0*2^5 + 0*2^4 + 0*2^3 + 1*2^2 + 0*2^1 + 0*2^0 = 4

Note: ^ indicate power

Consider on the union member variable a:

Data bit size: 2

Sign bit size: 1

Since a = 100 (In binary)

Data bit: 00

Sign bit: 1 (One means negative number)

Hence its equivalent decimal value is:

(-1)* 2^2 + 0*2^1 + 0*2^0 = - 4

13.

What will be the output if you will execute following c code?

#include<stdio.h>

int main() {

goto usa;

{

static int a=10;

usa: printf("%d",a);

}

return 0;

}

14.

What will be the output if you will execute following c code?

#include<stdio.h>

int main() {

int i=3,j=2,k=1;

printf("%d / %d");

return 0;

}

15.

The ‘continue’ keyword is used to

(A)	Continue the next iteration of a loop construct.
(B)	Exit the block where it exists and continues after.
(C)	Exit the outermost block even if it occurs inside the innermost.
(D)	Continue the compilation even an error occurs in a program.
(E)	None of these.

Explanation:

We can use continue keyword in case of loop. When program control encounter continue keyword it stop, that iteration after that line. And transfer the program control to beginning of the loop i.e. starts a new iteration if loop condition is true.

16.

Find the odd one out

17.

What is the value of EOF which is declared in "stdio.h"?

18.

Which data type behaves like both integer type and character type?

19.

What will be the output if you will execute following c code?

#include<stdio.h>

int main(){

struct node {

int data;

struct node *next;

};

struct node *p,*q;

p=(struct node *)malloc(sizeof(struct node));

q=(struct node *)malloc(sizeof(struct node));

p->data=10;

q->data=20;

p->next=q;

q->next=NULL;

printf("%d",p->data);

p=p->next;

printf("%d",p->data);

return 0;

}

20.

What will be the output if you will execute following c code?

#include<stdio.h>

int main(){

int x=2,*y=&x;

printf("%d",x*y);

return 0;

}

C programming Interview questions and answers

INDEX

c language questions and answers

2 comments:

(A)	Infinite loop
(B)	0 1
(C)	1
(D)	Stop after printing up to INT_MAX
(E)	Compilation error

(A)	Only (I) is correct.
(B)	Only (II) is correct.
(C)	Only (III) is correct
(D)	Only (I) and (II) are correct.
(E)	All are correct

(A)	Compiler gives an error message
(B)	It will return any garbage value.
(C)	It will return a cyclic value.
(D)	It will return zero or null value.
(E)	It will cause of run time error.

(A)	Associativity rule
(B)	Precedence rule
(C)	Left-right rule
(D)	Right-left rule
(E)	None of these

(A)	Device driver
(B)	Boot parameter
(C)	Bios
(D)	Modem
(E)	None of these

(A)	10
(B)	0
(C)	Warning, unreachable code
(D)	Garbage value
(E)	Error, unknown variable a.

(A)	0
(B)	-1
(C)	Any positive value
(D)	Any negative value
(E)	None of these

(A)	10 20
(B)	10 Garbage value
(C)	20 Garbage value
(D)	None of these
(E)	Compilation error

(A)	4
(B)	Garbage value
(C)	Prints result of multiplication of address of x and y
(D)	2
(E)	Compilation Error

(A)	#elif
(B)	#line
(C)	#else
(D)	#ifdef
(E)	#if