Question

Explain how records are represented in memory using array, with suitable examples of four records and four fields.

Answer 1

Each individual piece of data is called a field. A file is a collection of similar records. A data item can also be a group item made up of smaller sub-items.

Consider a record whose structure is given below

     1. Employee
          2. Name
             3. First name
             3. Last name
          2. sex
          2. Address
              3. City
              3. Pincode
          2. Phone no.

To store this record in memory, linear arrays are used.

A separate linear array is maintained for each basic element of the record, such as First Name, Last Name, Sex, City, Pincode, and Phone Number.

The figure below illustrates how the above record is represented using parallel linear arrays.

Records are stored in memory using parallel linear arrays. For any index K, the elements First Name[K], Last Name[K], Sex[K], and so on correspond to the same record in the file; that is, the Kth record in the file.

Suppose we have 4 fields:

• Roll No
• Name
• Class
• Marks

And 4 records (students):

Roll No	Name	Class	Marks
1	Amit	10	85
2	Neha	10	90
3	Rahul	10	78
4	Sneha	10	88

Representation in Memory using Parallel Arrays:

RollNo[ ] = {1, 2, 3, 4}

Name[ ] = {Amit, Neha, Rahul, Sneha}

Class[ ] = {10, 10, 10, 10}

Marks[ ] = {85, 90, 78, 88}

RollNo[2], Name[2], Class[2], Marks[2] → 3rd record (Rahul, 10, 78)