PYTHON FUNDAMENTALS
Python Character
Set :
It is a set of valid characters that a language recognizes.
Letters: A-Z, a-z Digits : 0-9 Special Symbols Whitespace
TOKENS
Token: Smallest individual unit in a program is known as token
There are five types of token in python:
1.
Keyword
2.
Identifier
3.
Literal
4.
Operators
5.
Punctuators
1. Keyword: Reserved words in the library of a language. There are 33 keywords in Python.
|
False |
class |
finally |
is |
return |
break |
|
None |
continue |
for |
lambda |
try |
except |
|
True |
def |
from |
nonlocal |
while |
in |
|
and |
del |
global |
not |
with |
raise |
|
as |
elif |
if |
or |
yield |
|
|
assert |
else |
import |
pass |
|
|
All the keywords are in lowercase except 03 keywords (True, False, None).
2. Identifier: The name given by the user to the entities like variable name, class-name, function-name, etc.
§ It can be a combination of letters in lowercase (a to z) or uppercase (A to Z) or digits (0 to 9) or an underscore.
§ It cannot start with a digit.
§ Keywords cannot be used as an identifier.§ We cannot use special symbols like !, @, #, $, %, + etc. in identifier.
§ _ (underscore) can be used in an identifier.
3. Literal: Literals are the constant
value. Literals can be defined
as a data that is given in a variable
or constant.
A. Numeric literals: Numeric Literals are immutable.
eg.
7, 8.7, 5+9j
B. String literals:
String literals can be formed by enclosing a text in the quotes. We can use both single as well as double quotes for a String.
Eg:
"Ramesh" , '12345'
Escape sequence characters:
|
\\ |
Backslash |
|
\’ |
Single quote |
|
\” |
Double quote |
|
\a |
ASCII Bell |
|
\b |
Backspace |
|
\f |
ASCII Formfeed |
|
\n |
New line charater |
|
\t |
Horizontal tab |
C. Boolean literal: A Boolean
literal can have any of the two values: True or
False.
D. Special literals: Python contains one special literal i.e. None.
None is used to specify to that field that is not created. It is also used for end of lists in Python.
E. Literal Collections: Collections such as tuples, lists and Dictionary are used in Python.
· int( ) - constructs an integer number from an integer literal, a float literal or a string literal.
Example:
x = int(1) # x will be 1
y = int(2.8) # y will be 2
z = int("3") # z will be 3
· float( ) - constructs a float number from an integer literal, a float literal or a string literal.
Example:
x = float(1) # x will be 1.0
y = float(2.8) # y will be 2.8
z = float("3") # z will be 3.0
w = float("4.2") # w will be 4.2
· str( ) - constructs a string from a wide variety of data types, including strings, integer literals and float literals.
Example:
x = str("suresh1") # x will be 'suresh1'
y = str(2) # y will be '2'
z = str(3.0) # z will be '3.0'
1. ArithmeticOperators:
2. Relational Operators/ComparisonOperator
