fundamental of python class 11 cbse part 1

PYTHON FUNDAMENTALS

CHARACTER SET

• It is a group of letters and signs which are specific to a language.
• Set include letter, sign, number, symbols.

1. Letter:A-Z, a-z.
2. Digit: 0-9.
3. special symbols: -,=,*,/,',(,) etc.
4. White spaces: blank space, tab, carriage, return, newline, formfeed etc.
5. Other character: Python can process all character of ASCII and UNICODE.

TOKENS

• Tokens is the smallest unit of any programming language.It is also known as Lexical unit.

Types of token are-

1. keyword
2. Identifiers
3. Literals
4. Operators 
5. Punctuators

KEYWORDS

• Keywords are those words which provides a specific meaning to interpreter.
• These are reserved for specific functioning.
• These can not be used as identifiers ,variable name or any purpose. 

               eg. false, class, if, or.

IDENTIFIERS

• Theses are building blocks of a program and are used to give names to different parts/blocks of a program like variable, objects, classes, functions.
• An identifier may be combination of letter and numbers.
• An identifier must begin with an alphabet or an underscore ( _ ). Subsequent letters may be number (0-9).
• Uppercase and lowercase has different meaning.
• Length of an identifier is unlimited.
• Keywords can not used as an identifier.
• Ex. Myfile, Date_9_0_12.

LITERAL / VALUES 

• Literal are also called constant values.
• Python permits following types of literals.

1.  String literals.
2. Numeric literals.
3. Boolean literals.
4. Special literals.
5. Literal collection.

String literals

• String literals is sequence of characters that can be a combination of letters, numbers and special symbols, enclosed in quotation mark, single, double, triple. (' '," ","' "').
• Types of string

1. Single line string: Text ="hello world" or Text = 'hello world'.
2. Multi line string: Text= 'hello/ or Text=

                                                 world'

Numeric literals

numeric values can be of 3 types-  

INT.  

• Decimal int. literal - 10,17,210 etc.
• Octal int. literal - 0o17, 0o217 etc.
• Hexa decimal int.- 0x14 etc.           

FLOAT (floating point real value)

• Fraction form - 2.5 , 4534.456+3455.434, etc.
• Exponent form - 1.8E+5. etc.

COMPLEX ( complex numbers)

• 3+5i etc.

BOOLEAN LITERAL

• It can contain either of only 2 values- true or false.

SPECIAL LITERALS

• None, which means nothing(no value)

             x= none

OPERATORS

• An operator is symbol that trigger some action when applies to identifiers (s)/ operand(s).
• Therefore, an operator requires operand (S) to computer upon.

             Eg: C=a+b

    Types of operators

1. Uniary Operators.
2. Binary Operators.

PUNCTUATORS

• In Python, punctuator are used to construct the program and make balance between instruction and statements Punctuators have their own synthetic semantic significance.  
• EX. /.;'=- etc.