Variable Types
Assigning values to variables
Python variables do not need explicit declaration to reserve memory space. This declaration happens automatically when you assign a value to a variable. The equation sign (=) is used to assign values to variables.
The operand to the left of the = operator is the name of the variable and the operand to the right of the = operator is the value stored in the variable. For example:
| Counter = 100 #An integer Assignmentmiles = 1000.0 # A floating Point name = ” prem” #A String String Print(counter) Print(miles) Print(name) |
Here, 100, 1000.0, and “prem” are the values assigned to counter, miles, and name variables respectively . This produce the following result:
| 100 1000.0 Prem |
Multiple Assignment
Python allows you to assign a single value to several variables simultaneously. For example:
| a = b = c = 1 |
Here, an integer object is created with the value 1, and all three variables are assigned to it. You can also assign multiple objects to multiple variables, for example :
| a, b, c = 1, 2, “Mechomotive” |
Here, two integer objects with values 1 and 2 are assigned to variables ‘a’ and ‘b’ respectively, and one string object with the value “Mechomotive” is assigned to the variable ‘c’.
Standard 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:
- Numbers
- Strings
- List
- Tuple
- Dictionary
1) Python Numbers
Number data types store numeric values. Number objects are created when you assign a value to them. For example :
| del var1[, var2[, var3[………., varN]]] |
You can delete a single object or multiple objects by using the del statement.
| del var del var_a, var_b |
Python supports four different numerical types :
- Int ( signed integer)
- Long (long integer, they can also be represented in octal and hexadecimal)
- Float ( floating point real values)
- complex ( complex numbers)
2) Python Lists
Lists are the most versatile of python’s compound data types l. A list contains items separated by commas and enclosed within square brackets ([]). To some extent, list are similar to arrays in C. One difference between them is that all the items belongs to a list can be of different data type.
The values stored in a list can be accessed using the slice operator ( [ ] and [ : ] ) with index starting from 0 in the beginning. For example :
| list = [ ‘abcd’, 786, 2.23, “prem”, 70.2] tinylist = [123, ‘prem’ ] print( list) # prints complete list print( list[1:3] ) # prints elmts starting from 2nd to 3rd |
This produces the following results :
| [‘abcd’, 786, 2.23, ‘prem’, 70.200000000000003] [786, 2.23] |
3) Python Tuples
A tTuple 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 difference 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 read-only lists . For example :
| tuple = ( ‘ abcd’, 786, 2.23, ‘prem’, 70.2) tinytuple = ( 123, ‘ prem’) print( tuple) print(tuple[1:3] ) |
This produce the following result :
| ( ‘ abcd’, 786, 2.23, ‘prem’, 70.200000000000003) (786, 2.23) |
4) Python 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 string. 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 ([]). For example :
| dict = {} dict[‘ one’ ] = ” This is one” tinydict = {‘name’ : ‘prem’, code : 6734,’dept’ : ‘sales’ } print( dict[‘one’ ] ) print(tinydict.keys()) |
| OUTPUT : This is one [‘dept’, ‘code’, ‘name’] |
Dictionaries have no concept of order among elements. They are simple unordered.
# Basic syntax and Variable types in Python
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