Variables and Data Types

Variables and Data Types

A variable is a name given to a memory location in a program. For example

a=30

 

b=”alok”

 

c=71.22

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Variable – Container to store a value

Keywords – Reserved words in Python

Identifiers – class/function/variable name

Data Types:

Primarily there are the following data types in Python:

1.     Integers

2.     Floating point numbers

3.     Strings

4.     Booleans

5.     None

Python is a fantastic language that automatically identifies the type of data for us.

a = 71                                    #Identifies a as class<int>

 

b = 88.44                              #Identifies b as class<float>

 

name = “alok”                  #Identifies name as class<Str>

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Rules for defining a variable name: (Also applicable to other identifiers)

• A variable name can contain alphabets, digits, and underscore.
• A variable name can only start with an alphabet and underscore.
• A variable can’t start with a digit.
• No white space is allowed to be used inside a variable name.

Examples of few valid variable names,

Alok, alok, one8, _akki, aakash, alok_bro, etc.

Operators in Python

The following are some common operators in Python:

1.     Arithmetic Operators (+, -, *, /, etc.)

2.     Assignment Operators (=, +=, -=, etc.)

3.     Comparison Operators (==, >=, <=, >, <, !=, etc.)

4.     Logical Operators (and, or, not)

type() function and Typecasting

type function is used to find the data type of a given variable in Python.

a = 31

 

type(a)                      #class<int>

 

b = “31”

 

type(b)                      #class<str>

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A number can be converted into a string and vice versa (if possible)

There are many functions to convert one data type into another.

Str(31)           # ”31” Integer to string conversion

 

int(“32”)       # 32 String to int conversion

 

float(32)       #32.0 Integer to float conversion

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… and so on

Here “31” is a string literal, and 31 is a numeric literal.

input() function

This function allows the user to take input from the keyboard as a string.

a = input(“Enter name”)               #if a is “alok”, the user entered alok

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Note: The output of the input function is always a string even if the number is entered by the user.

Suppose if a user enters 34, then this 34 will automatically convert to “34” string literal.

Chapter 2 – Practice Set

1.     Write a Python program to add two numbers.

2.     Write a Python program to find the remainder when a number is divided by Z(Integer).

3.     Check the type of the variable assigned using the input() function.

4.     Use a comparison operator to find out whether a given variable a is greater than b or not. (Take a=34 and b=80)

5.     Write a Python program to find the average of two numbers entered by the user.

6.     Write a Python program to calculate the square of a number entered by the user.