Python-02| Input, Output & Import

 Python 2.7 offers two functions
a) raw_input()
b) input()
 Python 3.x (latest release) the raw_input() has been
renamed as input() and the old input() function (of
release 2.x) has been removed.

The raw_input() is used as:
variable = raw_input(<statement>)
For example:
name = raw_input(‘What is your name’)
The data you type will be save to variable ‘name’
The raw_input() always returns a string type. In above example the python
interpreter returns the value of age(i.e., 18) in string type.
See the next slide to clear this concept.

 Python through an error, as Python cannot add integer to a
string.
 It received 12 through raw_input() as a string.
 We required to use typecasting functions with
raw_input()/input() [of python 3.x]

•Python offers two function int() and float() to convert the value in
integer and float type.
•bool() can also be used to get data in true/false

Python will through an error if you entered string type using raw_input() inside
int() or float()

 This input() function works only in Python 2.x.
 It does not supported by Python 3.x although Python uses
input() but actually it is raw_input() renamed as input().
 The input() returns value accordingly i.e., whatever type we
provide the same will be considered.
 It doesn’t require type casting.
On some installation it doesn’t work properly and raise error thus it should be
avoided and raw_input() should be used.

In Python 3.x, this input() has been removed and uses
raw_input() which has been renamed as input().
Input() function in Python 3.x should require typecasting
as it also generate data in string type by default.

To take input from user we took two input function and two lines. What
if we want this process in one single line? See next slide for answer
This is multiple input in one line. What if I want to use only one input()
function to take multiple inputs?

 For this we use split() function
a, b = input(“Enter first and last name”).split()
Note in Python code,
both a and b would be
of string.
We can convert them
to int using
a, b = [int(a), int(b)]
We can also use list
comprehension, will discuss in
next slide

a, b = [int(x) for x in input(“Enter two number:”).split()]
 split() is a function/method used to split the input() function
into multiple values.
 The method split() returns a list of all the words in the string.
 split() is opposite of concatenation which combines strings
into one.
List of multiple values

Note in the output window, user enter 3 values separated by spaces.
By default i.e., if no separator is defined in split() , space will be used
by default.

Input(“Enter two number”)
10 20
This will considered as one string but split() divide this string
into two with respect to space between them
10 | 20

Separated by
comma
Python will through error if not
separated by comma
Separation can be done using any of the other argument
split(“:”), split(“s”), split(“5”), split(“#”)

Python uses print() function to produce output.
print “Hello”
print 5
print ‘hello’
print (“Hello world”)
print (5)
print (“sum of 2 & 3 is”, 2+3)
Example of Python 2.x
Example of Python 3.x

print() :- without argument print() function prints a
blank line.
Line separator

print(string) :- enclosed within quotes.
Allowed escape character

What is the difference between
print(“Hello”+ “World”) and
print(“Hello” , “World”)
No Space
with Space
First argument Second argument
print() function insert spaces between items automatically.

 If we don’t want a space as separator between
arguments then we can use sep attribute
Space is added automatically
between the arguments. This is by
default, we can change it and will
show you on next slide.
By default sep = ‘ ’

 It appends a newline automatically
 In Python 2.x, it appends a newline unless the
statement ends in a comma.
a, b = 10, 20 a, b = 10, 20
print “a=”, a print “a=”, a,
print “b=”, b print “b=”, b
a = 10 a = 10 b = 20
b = 20
Notice first print
statement ends
with a comma
output

As we have seen that print() automatically appends a
new line and a space between different object, this is by
default
The actual syntax of the print() function is
print(*objects, sep=‘ ’, end = ‘n’, file=sys.stdout, flush=false)

 %i ➔ int type
 %d ➔ int type
 %f ➔ float type
 %s ➔ str type
 Syntax
Print(“formatted string” %(variable list))

 {} ➔ replacement operator
 It is used to format our output to make it look
attractive.
 This can be done by using the str.format() method.
 {} specify the order in which it is printed.

No need of
ordering
0 for Love and 1 for movie

 The backslash ( ) character is used to escape
characters
What if want to print n......use double
backslash
Printing single quote ( ‘ )
Printing double quote ( “ )
Printing backslash using double backslash

 When our program grows bigger, it is a good idea to break
it into different modules.
 Module is a group of functions, variables, classes etc.
 A library is a collection of modules.
 Python module have a filename and end with the
extension .py
 Definitions inside a module can be imported to another
module or the interactive interpreter in Python. We use
the import keyword to do this.

Python-02| Input, Output & Import

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Python-02| Input, Output & Import