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;

}

Answer Option 1

Concept: 

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.

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

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.

Answer: Option 4

Explanation: 

Consider the following example 

#include <stdio.h>
int main()
{
       int arr[10] = {1, 2, 3, 4, 5, 6, 7};

       arr++;
       return 0;
}

Here arr++; mean that

arr = arr + 1 ;

which is wrong we can not change the base address of an array and it will generate an error.
another way to do that is by using pointers.

#include <stdio.h>
int main()
{
       int arr[10] = {1, 2, 3, 4, 5, 6, 7};

       int *p = arr;

       p++;
       return 0;
}

Here int *p = arr; new pointer variable will be created which will start pointing to the first element of the array.

and p++; will cause the pointer to start pointing to the next element of the array.

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.