C Interview Questions With Explanation

C multiple choice questions and answers


1.

The array a[j][k] is equivalent to

(A)	((base type*)a+(j*row length)+k)
(B)	*((base type*)a+(j*row length)+k)
(C)	*((base type)a+(j*row length)+k)
(D)	*((base type)a+(j*row length))
(E)	None of these

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Explanation:
**

2.

What will be output of the following c program?

#include<stdio.h>

int main(){

int a[]={6,7,8,9},i;

    compute(a);

    for(i=3;i>=0;i--)

         printf(“%d”,a[i]);

return 0;

}

compute(int *p){

int i;

    for(i=0;i<4;i++){

       *p=*p-1;

        p++;

    }

}

(A)	5 6 7 8
(B)	6 7 8 9
(C)	8 7 6 5
(D)	None of these
(E)	Compilation error

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Explanation:
**

3.

What will be output of the following c program?

#include<stdio.h>

int main(){

    int a[]={4,5,6,7,8},i,*p;

    for(p=a+4,i=2;i<=4;i++)

       printf(“%d”,p[-i]);

return 0;

}

(A)	6
(B)	6 5 4
(C)	8 7 6 5 4
(D)	6 7 8
(E)	Compilation error

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Explanation:
**

4.

What will be output of the following c program?

#include<stdio.h>

int main(){

    int a[2][2][3]={{1,2,3,6,7,8},

                    {5,7,9,3,4,1}

  };

    printf(“%d”,*(*(*(a+1)+1)+1));

return 0;

} 

(A)	5
(B)	3
(C)	4
(D)	6
(E)	Compilation error

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Explanation:
**

5.

What will be output of the following c program?

#include<stdio.h>

int main(){

    char str[]="HELLO";

    char *p= "HAI";

    str="INDIA";

    printf("%s",str);

    return 0;

} 

(A)	HELLO
(B)	HAI
(C)	INDIA
(D)	Compilation error
(E)	None of these

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Explanation:
**

6.

What will be output of the following c program?

#include<stdio.h>

int main(){

char * emp name= "raja";

printf("%s",emp name);

return 0;

}

(A)	raja
(B)	ra
(C)	r
(D)	Compilation error
(E)	None of these

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Explanation:

Invalid variable name. Except underscore there should not be any special character in name of variable even blank space.

7.

What will be output of the following c program?

#include<stdio.h>

int main(){

long int new=5l;

printf("%ld",new);

return 0;

}

(A)	5
(B)	51
(C)	0
(D)	Compilation error
(E)	None of these

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Explanation:
We can use c++ keyword in variable name in c programming. (But should not use , why ?)

8.

What will be output of the following c program?

#include<stdio.h>

int main(){

long int _=5l;

printf("%ld",_);

return 0;

}

(A)	5
(B)	51
(C)	0
(D)	Compilation error
(E)	None of these

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Explanation:

Underscore is valid identifier in c.

9.

What will be output of the following c program?

#include<stdio.h>

int  main(){

char * __WORLD__="world";

printf("%s ",__WORLD__);

return 0;

}

(A)	world
(B)	null
(C)	__WORLD__
(D)	Compilation error
(E)	None of these

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Explanation:

__WORLD__ is valid identifier in c programming language. But we should not write variable name in the forma like __xyx__, __TIME__. Why ? 

10.

What will be output of the following c program?

#include<stdio.h>

int main(){

char * __TIME__="world";

printf("%s ",__TIME__);

return 0;

}

(A)	world
(B)	null
(C)	w
(D)	Compilation error
(E)	None of these

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Explanation:

__TIME__ is valid identifier in c programming language but it ispredefine global identifier. So a variable not should not be globalidentifier like__TIME__, __DATE___, __FILE__ etc.

11.

What will be output of the following c program?

#include<stdio.h>

int main(){

long int a;

(float)a=6.5;

printf("%f",a);

return 0;

}

(A)	6.5
(B)	6.500000
(C)	7.000000
(D)	Compilation error
(E)	None of these

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Explanation:

After applying any operator in variable name it always give a value.

(type): urinary type casting operator is not exception for this.

It is similar to write

3456=5

It is invalid c statement. Because left side of assignment operator must be a variable not any constant.

12.

What will be output of the following c program?

#include<stdio.h>

int main(){

long int a,b=10;

++a=b++;

printf("%d  %d",a,b);

return 0;

}

(A)	10
(B)	0
(C)	11
(D)	Compilation error
(E)	None of these

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Explanation:

After applying any operator in variable name it always give a value.

(type): urinary type casting operator is not exception for this.

It is similar to write

3456=5

It is invalid c statement. Because left side of assignment operator must be a variable not any constant.

13.

What will be output of the following c program?

#include<stdio.h>

int main(){

long int a,b=5;;

~a=++b + ++b + ++b;

printf("%d  %d",++a,++b);

return 0;

}

(A)	5
(B)	6
(C)	7
(D)	Compilation error
(E)	None of these

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Explanation:

After applying any operator in variable name it always give a value.

(type): urinary type casting operator is not exception for this.

It is similar to write

3456=5

It is invalid c statement. Because left side of assignment operator must be a variable not any constant.

14.

What will be output of the following c program?

#include<stdio.h>

int main(){

int x;

int y;

x+y=10;

x=3;

printf("%d",y);

return 0;

}

(A)	10
(B)	7
(C)	Garbage value
(D)	Compilation error
(E)	None of these

---

Explanation:

After applying any operator in variable name it always give a value.

(type): urinary type casting operator is not exception for this.

It is similar to write

3456=5

It is invalid c statement. Because left side of assignment operator must be a variable not any constant.

15.

What will be output of the following c program?

#include<stdio.h>

int main(){

int x=5;

int y=10;

&x=y;

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

return 0;

}

(A)	5 10
(B)	10 5
(C)	10 10
(D)	Compilation error
(E)	None of these

---

Explanation:

After applying any operator in variable name it always give a value.

(type): urinary type casting operator is not exception for this.

It is similar to write

3456=5

It is invalid c statement. Because left side of assignment operator must be a variable not any constant.

16.

What will be output of the following c program?

#include<stdio.h>

int main(){

const a=10;

a=~a;

printf("%d",a);

return 0;

}

(A)	10
(B)	-11
(C)	12
(D)	Compilation error
(E)	None of these

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Explanation:

We cannot modify a const object.

17.

What will be output of the following c program?

#include<stdio.h>

int main(){

const _=10;

int *p=&_;

printf("%d",*p);

}

(A)	10
(B)	11
(C)	Any address
(D)	Compilation error
(E)	None of these

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Explanation:

We can assign address of const object to its pointer. Underscore is valid variable name.

18.

What will be output of the following c program?

#include<stdio.h>

int main(){

const int *a=12;

a++;

printf("%d",a);

return 0;

}

(A)	12
(B)	13
(C)	14
(D)	Compilation error
(E)	None of these

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Explanation:

Here address of variable a is constant not variable a. So we can modify variable a. Initial value of auto type data is garbage.

19.

What will be output of the following c program?

#include<stdio.h>

int main(){

const int *a=(const int * )12;

*a=(const int *)25;

printf("%d",a);

return 0;

}

(A)	12
(B)	25
(C)	Any address
(D)	Compilation error
(E)	None of these

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Explanation:

We cannot modify a const object. Here address of variable a is constant not variable a.

20.

What will be output of the following c program?

#include<stdio.h>

int main(){

int * const a=(int * const)12;

a=25;

printf("%d",a);

return 0;

}

(A)	12
(B)	25
(C)	Any address
(D)	Compilation error
(E)	None of these

 

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Explanation:

We cannot modify a const object. Here address of variable a is not constant but variable a is constant. So we cannot modify variable a.