Chapter 3. Variables and Datatypes
3.1. Keywords and Identifiers
Python codes can be divided into identifiers. Identifiers (also referred to as names) are described by the following lexical definitions:
identifier ::= (letter|"_") (letter | digit | "_")*
letter ::= lowercase | uppercase
lowercase ::= "a"..."z"
uppercase ::= "A"..."Z"
digit ::= "0"..."9"
This means
_abcd is a valid identifier where as
1sd is not. The following identifiers are used as reserved words, or keywords of the language, and cannot be used as ordinary identifiers. They must be spelled exactly as written here:
and del from not while
as elif global or with
assert else if pass yield
break except import print
class exec in raise
continue finally is return
def for lambda try
In Python we don't specify what kind of data we are going to put in a variable. So you can directly write abc = 1 and abc will become an integer datatype. If you write abc = 1.0 abc will become of floating type. Here is a small program to add two given numbers
>>> a = 13
>>> b = 23
>>> a + b
36
From the above example you can understand that to declare a variable in python , what you need is just to type the name and the value. Python can also manipulate strings They can be enclosed in single quotes or double quotes like
>>> 'India'
'India'
>>> 'India\'s best'
"India's best"
>>> "Hello World!"
'Hello World!'
