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Which of the following is illegal declaration in C language?

  • Q. Which of the following is illegal declaration in C language?
  • filter_dramaExplanation
    Answer is : D

    Concept –

    Option_1: A valid declaration in C.

    char *str is a single value which is a pointer to a character. When used as a string in C, it is implied that subsequent characters of the string are stored in subsequent memory addresses, until the end of the string which is marked with a NULL.

    Option_2: A valid declaration in C.

    Char str[20] is an array of maximum 20 characters. It is similar to char *str except that there is no requirement that the last character in the array be null.

    Option_3 – A valid declaration in C.

    char str[40] is an array of maximum 40 characters. It is similar to char *str except that there is no requirement that the last character in the array be null.

    Option_4: Not a valid declaration in C.

    char[] str is a declaration in Java, but not in C.

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Similar Questions

  • 1. Which of the following is the correct declaration of linked list?
  • filter_dramaExplanation
    Answer is : B

    Declaration syntax: For structure in C and C++

    struct tag_name

    {

    Datatype  variable_name;

    struct tag_name *pointer_variable;

    };

    Option 2:

    struct node

    {

    int data;

    struct node*link;

    }

  • 2. Which is compulsory function in C language? 
  • filter_dramaExplanation
    Answer is : A

    The correct answer is main().

     Key Points

    • When the operating system runs a program in C, it passes control of the computer over to that program.
    • It is not possible to execute the c program without main().

     Additional Information

    • In C programming, scanf() is one of the commonly used function to take input from the user.
    • The scanf() function reads formatted input from the standard input such as keyboards.
    • The printf() is a library function to send formatted output to the screen.
    • The function prints the string inside quotations.
  • 3.

    The for statement 

    for(expr1 ; expr2 ; expr3) is equivalent to

  • filter_dramaExplanation
    Answer is : C

    While loop:

    In the while loop, the expression is evaluated.  If it is non-zero, the statement is executed and the expression is re-evaluated. This cycle continues until expression becomes zero, at which point execution resumes after the statement. 

    For loop:

    In the case of for loop, expr1 is an assignment or function call, expr2 is a relational expression while expr3 is also an assignment or function call. The for loop basically assigns the value to a variable using expr1, expr2 is used to evaluate the expression, and expr3 is used to modify the value of expr2 so that the terminating condition is reached.

    This functionality can be achieved using the while statement as listed in option 3.

  • 4. With respect to linked lists and arrays, which of the following statements is INCORRECT?
  • filter_dramaExplanation
    Answer is : A

    Answer Option 1

    Concept: 

    Array

    Linked Lists ( Singly linked list )

    1. Array supports Random access to its elements.

    1. Linked list does not support Random access to its elements

    2. Array elements are stored in a contiguous manner.

    2.  Linked list elements are generally not stored in contiguous locations.

    3. In Arrays, new elements cannot be added dynamically due to their fixed size.

    3. In Linked Lists, an element can be easily added dynamically as the Linked list can dynamically grow or shrink as when needed

    4. Inserting a new element in an array is expensive compared to inserting a new element in a linked list. Because size is fixed we have to create a new Array entirely and copy all the elements to a new array along with the new element

    4. Inserting a new element in a Linked List is very simple. Just allocate space for the new node and update the references/pointers.

    5. Deleting an element from an array is expensive compared to deleting an element from a linked list. Because suppose we want to delete the very first element from the array then we need to shift all the right elements to one position left.

    5. Deletion in the linked list is simple just deallocate the node and change the references/pointers.

    6. In Arrays there is no extra space/variables is allocated.

    6. In the Linked List, pointers are maintained for every node in order to keep track of all the nodes in the list.

     

    Explanation: 

    Option 1: The linked list is slower in add and remove, but faster in get.

    This is the only option that is incorrect since Linked list adding and removing the given element is faster as compared to an array but finding a particular indexed element we might have to traverse to entire list but in case of array random access possible.

  • 5.

    A binary tree T has n leaf nodes, the number of nodes of degree 2 in T is:

  • filter_dramaExplanation
    Answer is : B

    In an "m-ary" tree. the number of total nodes (N) is given by

    N=mi + 1  ----(1)

    Where,

    i: Number of internal nodes

    Also, in a tree, N=i + L   ----(2)

    Where,

    L=number of leaf nodes

    Here m=2

    From equation (1) and equation (2);

    N = 2i + 1

    2i + 1 = i + L

    L = i + 1

    The number of leaves are 1 plus the number of internal nodes in binary tree.

    Here, given L=n, substitute above and we will get,

    i = L - 1

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