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VALUES AND DATA TYPES
Learning Objectives
3.1 Character Sets in Java 3.2 How Characters are Stored in Memory?
3.3 Escape Sequences 3.4 Tokens
3.5 Data Types 3.6 Variables and Constants
3.7 Declaration vs Initialization 3.8 Type Conversion
A program is a collection of instructions. These instructions are written using a programming language. Before writing
a program, we need to understand the fundamental concepts of the programming language.
In this chapter, we will learn about different fundamental concepts of a Java programming language.
3.1 CHARACTER SETS IN JAVA
A character set is a set of letters, digits and special characters that a programming language can support. Every
programming language has its own character set. Similarly, Java also has its own character set. Java character set
includes the following:
• Letters: All the letters of the English language (A–Z) or (a–z).
• Digits: Digits from 0 to 9 can be used in Java programming.
• Special Characters: These are the symbols or signs used to specify a function to be performed in Java programming.
For example, +, &&, <=, ++, ( ), { }, [ ], comma(,), dot(.), semicolon(;), question mark(?), colon(:), etc.
3.2 HOW CHARACTERS ARE STORED IN MEMORY?
A computer is a man-made machine. It isn't capable of recognising anything from the 'human world' directly as it
understands numeric values (binary values). To store character values, corresponding numeric values in binary form
are generated. Thus, the characters entered have to be encoded into their numeric form. There are mainly two types
of encoding techniques which are ASCII code and Unicode. Let us learn about them.
3.2.1 ASCII Code
ASCII stands for American Standard Code for Information Interchange. It is a character encoding standard for text files in
computers and other devices. It is made up of 128 symbols consisting of letters (both uppercase and lowercase), numbers,
punctuation marks, special characters and control characters. It uses 7-bit numeric codes to represent characters. For
example, the ASCII value of character 'A' is 65 and the 7-bit code is 1000001. The numeric range of ASCII codes is from
0 to 127. It was designed to represent only basic English characters.
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Values and Data Types 33

