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Basics of Python


Now that you have a good command on previous chapter, let's do something more.

  • Python 2
  • Python 3
print type('Hello World')
print type(8)
print type(8.0)
print(type('Hello World'))
print(type(8))
print(type(8.0))
Output
<class 'str'>
<class 'int'>
<class 'float'>

'type()' gives us the type of anything given to it. For example, type("Hello World") is 'str'. str understands for string.

String is a collection of characters. In simple English, it is a letter, word, sentence or collection of sentences. You will go through a whole topic on string. So, leave it for that time. For now, just understant that a string is collection of characters and these are written between ' ' or " ". So, Hello World written between ' ' i.e. 'Hello World' is a string.

Similarly, int is for integers and float is for decimals.

Notice that simple 8 is an int but 8.0 is a float.
Even a digit written inside ' ' or " " is treated as a string and not as an integer or a decimal. For example, print(type("8")) will give us <class 'str'>.

Let's brush-up.

  • Python 2
  • Python 3
a = "I am learning something new."
b = 10
pi = 3.14
print type(a)
print type(b)
print type(pi)
print a
print b
print pi
a = "I am learning something new."
b = 10
pi = 3.14
print(type(a))
print(type(b))
print(type(pi))
print(a)
print(b)
print(pi)
Output
<class 'str'>
<class 'int'>
<type 'class'>
I am learning something new.
10
3.14

Python Keywords


There are few words which are used by Python language itself. So, we can't use those words for the name of our variables as they are reserved for the Python. For example, del is used to delete objects and using it for the name of a variable will give us an error.

Here is the list of keywords reserved for Python.

and def yield if not return
assert del finally import or try
break elif for in pass while
class else from is nonlocal yelid
continue except global lambda raise False
True None with as

Let's have some fun


  • Python 2
  • Python 3
print 'Fun'*3
print('Fun'*3)
Output
FunFunFun
This code should mean "Fun"+"Fun"+"Fun".
So let's try this:
  • Python 2
  • Python 3
print "a"+"b"
print("a"+"b")
Output
ab

Working!
This is the Pythonic way to get your things done. These type of features of Python can be of good use for you in future.

'*' in python

Commenting


You can also include something in your code which won't be compiled and your computer will simply ignore that while running your code. Comments are written to make our code more readable. Comments are written after '#'. Comments written after '#' are single line comments. New line will not be a part of the comment

  • Python 2
  • Python 3
# I am using a variable x
x = 10
print x
# I am using a variable x
x = 10
print(x)
Output
10

You can also use multi-line comments. To use them write comments between ( ''' ''' ). Let's see this.

  • Python 2
  • Python 3
'''
Multiline comment
Using variable x and y.
'''
x = 10
y = 5
print x+y
'''
Multiline comment
Using variable x and y.
'''
x = 10
y = 5
print(x+y)
Output
15
comment in python

Why to use comments?


As mentioned earlier, it makes your code more understandable. Assume that you have written a software and after releasing it, you hired few good programmers for its maintenance. Without comments, it would be a very difficult job for them to understand your code. And most of the time it happens that the person who has written a code is not the one who is going to modify it. So, make a habit of writing good comments.

Swap


Swapping means interchanging the values of two variables. eg - if x is 10 and y is 5 then after swapping x will be 5 and y will be 10.
So, let's see how to do this.

  • Python 2
  • Python 3
x = 10
y = 5
x,y = y,x
print x
print y
x = 10
y = 5
x,y = y,x
print(x)
print(y)
Output
5
10

And it's done. Yes, I know it is easy and that's why I love Python.

There is no glory in practice but there is no glory without practice.


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