Python Data-types:

As we know that there are keywords to identify the variables_name that they are int, float or string.
Only by assigning values in variable_names the data-type is defined automatically.



In Python there are five standard datat-ypes
They are listed as follows:

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



Number

Python supports four different numerical types:
  1. int (signed integers)
  2. long (long integers [can also be represented in octal and hexadecimal])
  3. float (floating point real values)
  4. complex (complex numbers)

var1=10                   # int
var2=30.3                 # float
var4=51924361L            # long
var5=3.14j                # complex



Note

Complex numbers are of the form

a+ib                      # where a is real part and b is imaginary part



Strings:

Strings are identified as a contiguous set of characters in between 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.

Note

The plus ( + ) sign is the string concatenation operator, and the asterisk ( * ) is the repetition operator. For example:
str = 'Hello World'

print str              #  Prints complete string 
print str[0]           #  Prints first character of the string 
print str[2:5]         #  Prints characters starting from 3rd to 5th 
print str[2:]          #  Prints string starting from 3rd character 
print str * 2          #  Prints string two times 
print str + "_string_2# " Prints concatenated string 



Output

Hello World
H
llo
llo World
Hello WorldHello World
Hello World_string_2



Python Lists:

Lists are the most versatile of Python's compound data types.
List contains items separated by commas and enclosed within square brackets ([]).
The values stored in a list can be accessed using the slice operator ( [ ] and [ : ]).
The plus ( + ) sign is the list concatenation operator, and the asterisk ( * ) is the repetition operator.


Example:

movies = ["The Holy Grail", "The Life of Brian", "The Meaning of Life", "Awatar", "Transformer"]
list = [12345, 'andru']
print movies # Prints complete list print movies[0] # Prints first element of the list print movies[0:2] # Prints elements starting from first till 3rd print movies[2:] # Prints elements starting from 3rd element print list * 2 # Prints list two times print movies + list # Prints concatenated lists



Output

["The Holy Grail", "The Life of Brian", "The Meaning of Life"]
The Holy Grail
["The Holy Grail", "The Life of Brian", "The Meaning of Life"]
["Awatar", "Transformer"]
[12345, 'andru'][12345, 'andru']
["The Holy Grail", "The Life of Brian", "The Meaning of Life", "Awatar", "Transformer", 12345, "andru"]

 



Python Dictionary

Python's dictionaries are kind of hash table type.
They consist of key-value pairs.
Dictionary keys can be almost any Python type, but are usually numbers or strings.




Note

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"

dict_2 = {'name': 'john','code':6734, 'dept': 'sales'}


print dict['one']           #  Prints value for 'one' key
print dict[2]               #  Prints value for 2 key
print dict_2                #  Prints complete dictionary
print dict_2.keys()         #  Prints all the keys
print dict_2.values()       #  Prints all the values



Output

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

var1=100
var2=30.3
var3="scanftree"
var4=51924361L 

print var1
print var2
print var3
print var4


In the next chapter you will to know basic operators python


Quantitative Aptitude
Reasoning
Programming
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