PYTHON FUNDAMENTALS
PYTHON FOR CBSE CLASS 11
Character Set is a valid set of characters that a language recognizes. It could be any letter, digit or any symbol. Python has the following character set:
| Letters | A – Z, a – z |
| Digits | 0 – 9 |
| Special Symbols | Space + – * / % // ( ) [ ] { } \ # , ; :: ‘ ‘ “ “ @ _ < > = & ** != == |
| Whitespaces | Blank Space, tabs, carriage return (enter sign), newline, formfeed |
| Other characters | Python can process all ASCII and UNICODE characters. |
TOKENS
The smallest individual unit in a program is called as Token or a lexical unit.
Python for cbse class 11 has following tokens:
Keywords Identifiers Literals Operators Punctuators
Keywords: A keyword is a word having special meaning reserved by programming language.
Eg:- False, True, print, id, and, or, not
Identifiers: Identifiers are the names build by programmer and are used in program but are not keywords. Python has some rules to form an identifier –
— An identifier is a long sequence of letters and digits with unlimited length.
— The first character could be a letter or an underscore ( _ ).
— Upper case and lower case is differently processed i.e. A is not process as a.
Python is case sensitive language.
— The digit 0 to 9 could be a part of identifier but cannot be the first character.
— Identifier cannot contain any special character.
Eg:- Valid Identifiers: Name _DT Z12345 My_File
Invalid Identifiers: 29Abc My.File False dat$comp
Literals / Values: Literals are also called constant values are data items have fixed values.
Python allows following literals.
— String Literals: These are created by enclosing text in single quotes or double quotes.
Eg: “ Hello World “ , ‘ My name is Sara ‘
— Numeric Literals: These could be integer types, floating types or complex types.
Integer literal: These are whole numbers without any fractional part. These could be positive ( + ) or negative ( – ). Eg: 125, -78, +86
Floating literal: These have fractional part and could be represented in Fractional form or Exponent form. Eg: 13.8, 2.0, -63.556 (fractional)
1.7E, 0.58E02 (exponent form)
— Boolean literal: This could be either 0 or 1. 1 means True and 0 means False.
— Special Literal None: The None literal indicates the absence of value. It is also used to
indicate the end of the lists in Python.
Operators: These are used to perform operations on values and variables. They trigger some
computation.
— Unary Operators: They only need one operand to operate upon.
+ Unary Plus (Eg: +63, 951)
- Unary Minus (Eg: -25, -3.65)
~ Bitwise Complement (Eg: 8 bits- complement(0) is 11111111 )
not Logical negation (Eg: if x = 1, not x = 0 )
— Binary Operators: They need two operand to operate upon.
Arithmetic Operators ( + – * / // % ** )
Identity operators ( is is not )
Relational Operators ( < > <= >= == != )
Assignment Operators = /= += -= %= //= **= *=
Logical Operators and or
Membership Operators in not in
Punctuators: Theses are symbols that are used in programming languages to organize structures,
statements, expressions.
Eg: ‘ “ # \ ( ) { } [ ] @ : , =
