# REPRESENTATION OF DATA / INFORMATION

What is Data ?

As you learnt earlier, data refers to the symbols that can be a name, number, etc. Data are isolated values or raw facts which by themselves do not have much significance.

Information is processed, manipulated and interpreted data. It is created by defining and organizing relationship among various kind of data.

Data representation refers to the form in which data is stored, processed and transmitted. It also refers to the methods used internally to represent information stored in a computer. Computer can store lots of different types of information such as numbers, text, graphics, sound, etc.

Basic Data Types

“Data type is a term that is used to show the kind of data values or the type of data that is expected to be handled.”

A data type is a classification of the data type that a variable can hold in computer programming.

(i) Integer Data Type Integer is the whole number having different storage range supported by particular machine. Integer data type is used to store whole number using different memory spaces. Integer has no fractional parts. Integer can be positive or negative. Generally, an integer takes 2 bytes in memory and the range of values is from -32768 to +32767.

(ii) Character Data Type The character data type is used to store the alphanumeric character. If a character from this set is stored in a character variable, its value is equivalent to the ASCII code of that character and requires only one byte of memory to save. Size of character is 1 byte that ranges from -128 to +127.

(iii) Float Data Type The number having fractional part is a floating point number. The decimal point signals is a floating point number not an integer. Floating point numbers are represented by using float keyword.

Floating point numbers are used for measurable quantities like distance, area, temperature, etc., and typically have fractional parts. It represents real numbers. It occupies 4 bytes of memory.

(iv) Double Data Type This data type is used for double precision floating point numbers. Double data type occupies twice as much memory as float type and stores floating point numbers with much larger range and precision. It is used when float type is too small or insufficiently precise. The size of double type variable is 8 bytes.

(v) Void Data Type This data type is used for empty set of values. Also, it is used as the return type for functions, which do not return any value. No object of type void may be declared.

Computers can not understand what you give as input. Input is converted into a form so that computers be able to understand it. A computer can only understand positional number system.

Positional number system contains few symbols called digits. Each digit is used to represent a value depending on its base and position, they appear in a number. Base is reffered as total number of the digits available in a number system.

Following are some number systems :

(i) Binary Number System

Binary number system consists of only two digits 0 and 1. All data is converted in the form of 0 and 1 (Combination of 0 and 1).Digital computers work on binary system. Base for binary number is 2, which plays a vital role in converting a number into binary or its acutal form.

(ii) Decimal Number System

Decimal number system contains 10 symbols to represent a number. In this number system, total 10 digits are used so the base of this number system is 10. Any number which contains 0 to 9 digits or consists of these digit can be represented as decimal number.

(iii) Octal Number System

This number system contains 8 symbols to represent a number. So base for octal number is 8 and digits are used from 0 to 7. If any number contains other digit like 9, 10 and so on,  then it is not an octal number. Numbers like 129,228 are not octal numbers because 9 and 8 digits do not belong to octal number.

There are 16 unique digits available in this number system. These are 0 to 9 and A to F, where A denotes 10- B denotes 11, C denotes 12, D denotes 13, E denotes 14and F denotes 15.As, this number system Has 16 digits so it is called base 16 number system also. Each position of the hexadecimal number represents a successive power of 16.

Concept of Data Processing

Data processing is the act of handling or manipulating data. It is the process through which facts and figures are collected, assigned meaning, communicated to others and retained for future use. “Data processing is a series of actions or operations that converts data into useful information”.

There are five steps for data processing:

(i) Collect data

(ii) Prepare data

(iii) Input data

(iv) Process data

(v) Output or information

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