Array and two-dimensional array, Data Structure & Algorithms

Q. Describe the term array.  How do we represent two-dimensional arrays in memory?  Explain how we calculate the address of an element in a two dimensional array.                                                

Ans:

An array is a systematic arrangement of objects generally in rows and columns

Each memory location is defined by an array element. An array element is similar to one variable except it is identified by an index value as a substitute of a name. An index value is a number used to recognize an array element.

Declaration of a two dimensional array- A two dimensional array is declared similarly as we declare a one-dimensional array except that we specify the number of elements in both dimensions. Such as,

int grades[3][4];

The first bracket ([3]) tells the compiler that we are declaring 3 number of pointers, each of them pointing to an array. Here we are not talking about a pointer variable or pointer array. Instead of that, we are saying that each element of the first dimension of a two dimensional array reference a corresponding second dimension. In the above example, all the arrays pointed to by the first index are of the same size. The second index may be of variable size. For example, the earlier statement declares a two- dimensional  array  where  there  are  3  elements  in  the  first  dimension  and  4 elements in the second dimension array.

Two-dimensional array can be represented in memory by following two ways:

1.  Row major representation: To attain b this linear representation, the first row of the array is stored in the first memory locations reserved for the array, then the second row and this process continues.

2.  Column major representation: In this elements of the column are stored next to one another.

In row major representation, the address is always calculated in a two dimensional array as per the formula written below. The address of a[i][j]=base(a)+(i*m+ j)*size in which base(a) is the address of a[0][0], m is second dimension of array a and size represent size of the data type.

Posted Date: 7/10/2012 3:37:49 AM | Location : United States







Related Discussions:- Array and two-dimensional array, Assignment Help, Ask Question on Array and two-dimensional array, Get Answer, Expert's Help, Array and two-dimensional array Discussions

Write discussion on Array and two-dimensional array
Your posts are moderated
Related Questions
N = number of rows of the graph D[i[j] = C[i][j] For k from 1 to n Do for i = 1 to n Do for j = 1 to n D[i[j]= minimum( d ij (k-1) ,d ik (k-1) +d kj (k-1)

The number of interchanges needed to sort 5, 1, 6, 2 4 in ascending order using Bubble Sort is 5

The maximum degree of any vertex in a simple graph with n vertices is (n-1) is the maximum degree of the vertex in a simple graph.

Implement multiple stacks in a single dimensional array. Write algorithms for various stack operations for them.

(i)  Consider a system using flooding with hop counter. Suppose that the hop counter is originally set to the "diameter" (number of hops in the longest path without traversing any

Linear search employee an exhaustive method of verified each element in the array against a key value. Whereas a match is found, the search halts. Will sorting the array before uti

write short note on algorithms

Example 3: Travelling Salesman problem Given: n associated cities and distances among them Find: tour of minimum length that visits all of city. Solutions: How several

Double Linked List In a doubly linked list, also known as 2 way lists, each node is separated into 3 parts. The first part is called last pointer field. It has the address of t

#question. merging 4 sorted files containing 50,10,25,15 records will take time?