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Interview based question and answers in C lanaguage

Interview based question and answers in C lanaguage

C is a high-level and general-purpose programming language that is ideal for developing firmware or portable applications.

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1) What is the use of a ‘\0’ character?
Ans:-It is referred to as a terminating null character, and is used primarily to show the end of a string value. 
2) Write a C program to print hello world without semi colon?


void main(){
    if(printf("Hello world")){
3) Write a c program to check given number is perfect number or not.
int main(){
  int n,i=1,sum=0;
  printf("Enter a number: ");
          i++;  }
      printf("%d is a perfect number",i);
      printf("%d is not a perfect number",i);
  return 0;} 
4) Write a C program to print Fibonacci series using recursive function in C.
 int Fibonacci(int);
 int main()
   int n, i = 0, c;
    printf("Fibonacci series\n");
    for ( c = 1 ; c <= n ; c++ )   {
      printf("%d\n", Fibonacci(i));
      i++;    }
    return 0;}
int Fibonacci(int n){   if ( n == 0 )
      return 0;
   else if ( n == 1 )
      return 1;
      return ( Fibonacci(n-1) + Fibonacci(n-2) );}
 5) How to call C functions in a program?

Ans:-(i)Call by value
(ii)Call by reference
 6) What are the uses of C function?
Ans:-(i)C functions are used to avoid rewriting same logic/code again and again in a program.
(ii)There is no limit in calling C functions to make use of same functionality wherever required.
(iii)We can call functions any number of times in a program and from any place in a program.
(iv)A large C program can easily be tracked when it is divided into functions.
(v)The core concept of C functions are, re-usability, dividing a big task into small pieces to achieve the functionality and to improve understandability of very large C programs. 
7)What is the difference between Actual and Formal parameter?
Ans:-Actual parameter – This is the argument which is used in function call.
Formal parameter – This is the argument which is used in function definition 
8)Write a C program to find the greatest of 3 numbers?
void main() {
   int a, b, c;
   printf("\nEnter value of a, b & c : ");
   scanf("%d %d %d", &a, &b, &c);
   if ((a > b) && (a > c))
      printf("\na is greatest");
   if ((b > c) && (b > a))
      printf("\nb is greatest");
   if ((c > a) && (c > b))
      printf("\nc is greatest");
9)Write a C program to compute the sum of the array elements using pointers?
void main() {
   int numArray[10];
   int i, sum = 0;
   int *ptr;
   printf("\nEnter 10 elements : ");
   for (i = 0; i < 10; i++)
      scanf("%d", &numArray[i]);
   ptr = numArray; /* a=&a[0] */
   for (i = 0; i < 10; i++) {
      sum = sum + *ptr;
      ptr++;   }
   printf("The sum of array elements : %d", sum);}
10) C Language has been developed in which language?
Ans:-C language has been developed using assembly level language. 
11) What Is The Difference Between Assembler, Compiler And Interpreter?
Ans:-(i)Assembler is a program that converts assembly level language (low level language) into machine level language.
(ii)Compiler compiles entire C source code into machine code. Whereas, interpreters converts source code into intermediate code and then this intermediate code is executed line by line. 
12)What is Constant in C?
Ans:-Constants refer to fixed values. They are also called as literals.
C Constants are also like normal variables. But, only difference is, constant values can’t be modified by the program once they are defined. Constants may be belonging to any of the data type.
 13) What Is The Difference Between Strcpy() & Strncpy() Functions In C?
Ans:-strcpy( ) function copies whole content of one string into another string. Whereas, strncpy( ) function copies portion of contents of one string into another string.
If destination string length is less than source string, entire/specified source string value won’t be copied into destination string in both cases. 
14) What is const pointer in C?
Ans:-Const pointer is a pointer that can’t change the address of the variable that is pointing to.
Once const pointer is made to point one variable, we can’t change this pointer to point to any other variable. This pointer is called const pointer. 
15) What Is Dangling Pointer In C?
Ans:-When a pointer is pointing to non-existing memory location is called dangling pointer.
 16) What is the difference between malloc() and calloc()?
Ans:-(i)The name malloc stands for "memory allocation".The function malloc() reserves a block of memory of specified size and return a pointer of type void which can be casted into pointer of any form.
(ii) The name calloc stands for "contiguous allocation".The only difference between malloc() and calloc() is that, malloc() allocates single block of memory whereas calloc() allocates multiple blocks of memory each of same size and sets all bytes to zero.
 17) Write a C program to find sum of n elements entered by user. To perform this program, allocate memory dynamically using malloc() function.
Ans:-#include <stdio.h>
#include <stdlib.h>
void main(){
    int num, i, *ptr, sum = 0;
    printf("Enter number of elements: ");
    scanf("%d", &num);
    ptr = (int*) malloc(num * sizeof(int));  //memory allocated using malloc
    if(ptr == NULL)       
        printf("Error! memory not allocated.");
        exit(0);    }
    printf("Enter elements of array: ");
    for(i = 0; i < num; ++i)    {
        scanf("%d", ptr + i);
        sum += *(ptr + i);    }
    printf("Sum = %d", sum);
    free(ptr);   }
 18) How do you generate random numbers in C?
Ans:-Random numbers are generated in C using the rand() command. For example: anyNum = rand () will generate any integer number beginning from 0, assuming that anyNum is a variable of type integer.
 19) What are multidimensional arrays?
Ans:-Multidimensional arrays are capable of storing data in a two or more dimensional structure. For example, you can use a 2 dimensional array to store the current position of pieces in a chess game, or position of players in a tic-tac-toe program.
 20) What is Pointer on pointer?
Ans:-It’s a pointer variable which can hold the address of another pointer variable. It de-refers twice to point to the data held by the designated pointer variable.



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