MODULE I

Python input() Function

The input() function allows user input

Python output() Function

We use the print() function to output data to the standard output device (screen).

Output formatting

Sometimes we would like to format our output to make it look attractive. This can be done by using the str.format() method. This method is visible to any string object.

OUTPUT:
I love bread and butter
I love butter and bread

Python Import

When our program grows bigger, it is a good idea to break it into different modules.
A module is a file containing Python definitions and statements. Python modules 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.

We can also add our own location to this list.

Operators

Types of Operators Python language supports the following types of operators.

1. Arithmetic Operators
2. Comparison (Relational) Operators
3. Logical Operators
4. Bitwise Operators
5. Membership Operators
6. Identity Operators

Arithmetic Operators

Comparison Operators

Assignment Operators

Bitwise Operators

Bitwise operator works on bits and performs bit by bit operation. Assume if a = 60; and b = 13;

Logical Operators

Membership Operators

Identity Operators

Python Data Types

The data stored in memory can be of many types. For example, a person's age is stored as a numeric value and his or her address is stored as alphanumeric characters. Python has various standard data types that are used to define the operations possible on them and the storage method for each of them.

Python has five standard data types:

1. Numbers
2. String
3. List
4. Tuple
5. Dictionary

1. NUMBERS

Number data types store numeric values. Number objects are created when you assign a value to them.

Python supports four different numerical types:

• int (signed integers)
• long (long integers, they can also be represented in octal and hexadecimal)
• float (floating point real values)
• complex (complex numbers)

2. STRINGS

Strings in Python are identified as a contiguous set of characters represented in the quotation marks. Python allows for either pairs of single or double quotes. Subsets of strings can be taken using the slice operator ([ ] and [:] ) with indexes starting at 0 in the beginning of the string and working their way from -1 at the end.

The plus (+) sign is the string concatenation operator and the asterisk (*) is the repetition operator.

Example

	str = 'Hello World!' 
	print str     
	print str[0]   
	print str[2:5] 
	print str[2:]  
	print str * 2      # Prints string two times 
	print str + "TEST" # Prints concatenated string 

Output

	Hello World!
	H
	llo
	llo World!
	Hello World!Hello World! 
	

3. LISTS

Lists are the most versatile of Python's compound data types. A list contains items separated by commas and enclosed within square brackets ([]). To some extent, lists are similar to arrays in C. One difference between them is that all the items belonging to a list can be of different data type.

The values stored in a list can be accessed using the slice operator ([ ] and [:]) with indexes starting at 0 in the beginning of the list and working their way to end -1. The plus (+) sign is the list concatenation operator, and the asterisk (*) is the repetition operator.

Example

	list = [ 'abcd', 786 , 2.23, 'john', 70.2 ] 
	tinylist = [123, 'john'] 
 
	print list          # Prints complete list 
	print list[0]       # Prints first element of the list 
	print list[1:3]     # Prints elements starting from 2nd till 3rd  
	print list[2:]      # Prints elements starting from 3rd element 
	print tinylist * 2  # Prints list two times 
	print list + tinylist # Prints concatenated lists 
	

Output

	['abcd', 786, 2.23, 'john', 70.200000000000003] 
	abcd 
	[786, 2.23]
	[2.23, 'john', 70.200000000000003] 
	[123, 'john', 123, 'john'] 
	['abcd', 786, 2.23, 'john', 70.200000000000003, 123, 'john'] 
	

4. TUPLES

A tuple is another sequence data type that is similar to the list. A tuple consists of a number of values separated by commas. Unlike lists, however, tuples are enclosed within parentheses.

The main differences between lists and tuples are: Lists are enclosed in brackets ( [ ] ) and their elements and size can be changed, while tuples are enclosed in parentheses ( ( ) ) and cannot be updated. Tuples can be thought of as readonly lists.

Example

	tuple = ( 'abcd', 786 , 2.23, 'john', 70.2  ) 

	tinytuple = (123, 'john') 

 	

	print tuple           # Prints complete list 
	print tuple[0]        # Prints first element of the list 
	print tuple[1:3]      # Prints elements starting from 2nd till 3rd  
	print tuple[2:]       # Prints elements starting from 3rd element 
	print tinytuple * 2   # Prints list two times 
	print tuple + tinytuple # Prints concatenated lists 

Output

	('abcd', 786, 2.23, 'john', 70.200000000000003) 
	abcd 
	(786, 2.23) 
	(2.23, 'john', 70.200000000000003) 
	(123, 'john', 123, 'john') 
	('abcd', 786, 2.23, 'john', 70.200000000000003, 123, 'john') 
	

5. DICTIONARY

Python's dictionaries are kind of hash table type. They work like associative arrays or hashes found in Perl and consist of key-value pairs. A dictionary key can be almost any Python type, but are usually numbers or strings. Values, on the other hand, can be any arbitrary Python object.

Dictionaries are enclosed by curly braces ({ }) and values can be assigned and accessed using square braces ([]).

Example

	dict = {} 
	dict['one'] = "This is one" 
	dict[2]     = "This is two" 
	tinydict = {'name': 'john','code':6734, 'dept': 'sales'} 
	print dict['one']       # Prints value for 'one' key 
	print dict[2]           # Prints value for 2 key 
	print tinydict          # Prints complete dictionary 
	print tinydict.keys()   # Prints all the keys 
	print tinydict.values() # Prints all the values 

Output

	This is one 
	This is two 
	{'dept': 'sales', 'code': 6734, 'name': 'john'}
	['dept', 'code', 'name'] 
	['sales', 6734, 'john']
	

Decision Making

Decision making is anticipation of conditions occurring while execution of the program and specifying actions taken according to the conditions. Decision

if expression1: 
   statement(s) 
elif expression2: 
   statement(s) 
elif expression3: 
   statement(s)

Looping

A loop statement allows us to execute a statement or group of statements multiple times.

while expression: 
   statement(s) 
	

count = 0 
while count < 5: 
   print count, " is  less than 5" 
   count = count + 1 
	

for iterating_var in sequence: 
   statements(s) 
	

fruits = ['banana', 'apple',  'mango'] 
for fruit in fruits:        # Second Example 
   print 'Current fruit :', fruit 
	

for iterating_var in sequence: 
   for iterating_var in sequence: 
      statements(s) 
   statements(s)

while expression: 
   while expression: 
      statement(s) 
   statement(s) 
	

i = 2 
while(i < 100): 
   j = 2 
   while(j <= (i/j)): 
      if not(i%j): break 
      j = j + 1 
   if (j > i/j) : print i, " is prime" 
   i = i + 1 
 
print "Good bye!" 
	

Python Methods

String Method

List Methods

Tuple Methods

Dictionary Methods