This is Python tutorial no. 2
One thing you should note here is '>>>' in the tutorials is the python
prompt which implies that python interpreter is ready to interpret your
commands and '...' is padded with multiline statements by python shell,
they are not the part of input or output.So if you copy any examples from
here don't copy the '>>>' and '...'
The topics covered in this tutorial are :
1.Program input/output(often referred as I/O).
2.Operators
3.Variables
4.Indentation
# 1. Program I/O (if u remember this is a python comment... :) )
First we should learn about I/O which is basically everywhere
even in the Hello world program that we created in tutorial 1.
For output we use the print statement like this:
>>> print "Hi this is the output!"
You can use print with string format operator (%), it behaves exactly
One thing you should note here is '>>>' in the tutorials is the python
prompt which implies that python interpreter is ready to interpret your
commands and '...' is padded with multiline statements by python shell,
they are not the part of input or output.So if you copy any examples from
here don't copy the '>>>' and '...'
The topics covered in this tutorial are :
1.Program input/output(often referred as I/O).
2.Operators
3.Variables
4.Indentation
# 1. Program I/O (if u remember this is a python comment... :) )
First we should learn about I/O which is basically everywhere
even in the Hello world program that we created in tutorial 1.
For output we use the print statement like this:
>>> print "Hi this is the output!"
You can use print with string format operator (%), it behaves exactly
like C's printf() function.
>>> print "%s is number %d" % ("Python",1) # s for string and d # for integer
and for input we use the raw_input() .... we use it like this:
>>>x=raw_input("Enter the value of x:") # here x is a variable.
>>>x # if u write x and press enter
'2' # it shows the value of x.
>>> print "The value of x is", x # you can print variables
# by separating them with comma.
Note: You can use input() to take input too in Python 2.x but it poses
a security risk and it should not be used.
In Python 3.x raw_input() has been renamed as input() and the
old input() is no longer there in Python 3.x.
# 2.Operators
Mathematical operators:
+ ----> Addition Usage : c=a+b # a and b should not be mixed
# types.
# a=4 and b='string'
# c=a+b gives errror!!
- ----> Subtraction Usage : c=a-b # same with subtraction.
* ----> Multiplication Usage : c=a*b
/ ----> Division Usage : c=a/b
% ----> Modulus/Remainder Usage : c=a%b # Gives remainder of a/b
# works with integer
# and floating numbers both.
** ----> Exponentiation Usage : c=a**b # gives a raised to power b.
Comparison operators:
< ----> Less than Usage : c=a<b # Gives True when a is less than b
# otherwise False
<= ----> Less than or equal to Usage : c= (a<=b) # Gives True if a is
# less than or equal to b.
> ----> Greater than Usage : c=a>b # Gives True if a is greater than b.
# False otherwise.
>= ----> Greater than or equal to Usage: c=(a>=b) # Gives True
# when a is greater
# than or equal to
# b. False otherwise.
== ----> Equal to operator Usage : c= (a==b) # Gives True is a is
# equal to b.
# False otherwise.
= ----> Assignment Usage : c=b # Assigns value of b to c.
!= ----> Not equal to Usage : c=(a!=b) # Gives True if a is not equal to b.
Expression conjunction operators:
and ----> and operator Usage: c= a and b # Gives True if both a and b
# are both True. False
# otherwise.
or ----> or operator Usage: c= a or b # Gives True if both a and b are
# True. False otherwise.
not ----> not operator Usage: c= not a # Reverse the values of a.
Python does not have the increment (++n ) or decrement (--n) operator.
# 3.Variables
Rules for naming variables are simple:
1. Characters must be alphanumeric or underscore.
2. First character must not be a digit.
Python is case sensitive.So, var and VAR are two different variables.
Python is dynamically typed. So, you don't have to declare the varibles.
These are some declarations:
>>> x=2
>>> x_9 = 23 # Varible name with all possible characters.
>>> stri="This is a string " # a string
>>> 9gag=78 # First character must not be a digit.
SyntaxError: Invalid syntax
# 4.Indentation
Python uses indentation rather than curly braces. This increases readability
and it clearly identifies a block of code a statement belongs to.
This may seem a bit odd at the beginning but you may like it after some
time.Also, use either Tabs or spaces to indent the code. Mixing both can also
lead to indentation error..
So that's it for this tutorial....Share it with your friends if you liked it...
Next tutorial covers Python Types, Tuple, List, Dictionaries etc...
>>> print "%s is number %d" % ("Python",1) # s for string and d # for integer
and for input we use the raw_input() .... we use it like this:
>>>x=raw_input("Enter the value of x:") # here x is a variable.
>>>x # if u write x and press enter
'2' # it shows the value of x.
>>> print "The value of x is", x # you can print variables
# by separating them with comma.
Note: You can use input() to take input too in Python 2.x but it poses
a security risk and it should not be used.
In Python 3.x raw_input() has been renamed as input() and the
old input() is no longer there in Python 3.x.
# 2.Operators
Mathematical operators:
+ ----> Addition Usage : c=a+b # a and b should not be mixed
# types.
# a=4 and b='string'
# c=a+b gives errror!!
- ----> Subtraction Usage : c=a-b # same with subtraction.
* ----> Multiplication Usage : c=a*b
/ ----> Division Usage : c=a/b
% ----> Modulus/Remainder Usage : c=a%b # Gives remainder of a/b
# works with integer
# and floating numbers both.
** ----> Exponentiation Usage : c=a**b # gives a raised to power b.
Comparison operators:
< ----> Less than Usage : c=a<b # Gives True when a is less than b
# otherwise False
<= ----> Less than or equal to Usage : c= (a<=b) # Gives True if a is
# less than or equal to b.
> ----> Greater than Usage : c=a>b # Gives True if a is greater than b.
# False otherwise.
>= ----> Greater than or equal to Usage: c=(a>=b) # Gives True
# when a is greater
# than or equal to
# b. False otherwise.
== ----> Equal to operator Usage : c= (a==b) # Gives True is a is
# equal to b.
# False otherwise.
= ----> Assignment Usage : c=b # Assigns value of b to c.
!= ----> Not equal to Usage : c=(a!=b) # Gives True if a is not equal to b.
Expression conjunction operators:
and ----> and operator Usage: c= a and b # Gives True if both a and b
# are both True. False
# otherwise.
or ----> or operator Usage: c= a or b # Gives True if both a and b are
# True. False otherwise.
not ----> not operator Usage: c= not a # Reverse the values of a.
Python does not have the increment (++n ) or decrement (--n) operator.
# 3.Variables
Rules for naming variables are simple:
1. Characters must be alphanumeric or underscore.
2. First character must not be a digit.
Python is case sensitive.So, var and VAR are two different variables.
Python is dynamically typed. So, you don't have to declare the varibles.
These are some declarations:
>>> x=2
>>> x_9 = 23 # Varible name with all possible characters.
>>> stri="This is a string " # a string
>>> 9gag=78 # First character must not be a digit.
SyntaxError: Invalid syntax
# 4.Indentation
Python uses indentation rather than curly braces. This increases readability
and it clearly identifies a block of code a statement belongs to.
This may seem a bit odd at the beginning but you may like it after some
time.Also, use either Tabs or spaces to indent the code. Mixing both can also
lead to indentation error..
So that's it for this tutorial....Share it with your friends if you liked it...
Next tutorial covers Python Types, Tuple, List, Dictionaries etc...