Variable Declaration in python

 

Variable Declaration: A variable is nothing but a name given to a storage area that our programs can manipulate. A Variable is the heart of every good programming language, including Python. Variables are changed time to time, because they have dynamic nature.

A variable is nothing but a reserved memory location to store values. In other words, a variable in a program gives data to the computer to work on. Every value in Python has a data type. Different data types used in Python are Numbers, List, Tuple, Strings, Dictionary, etc. Variables can be declared by any name or even alphabets like total_amount, Marks, Sname, etc.

These are the following rules of writing variable in python programming-

·         Every variable starts with a character, underscore "_" or a upper-case  or lower-case letter.

·         Always variable must be start with alphabet after that we can use number. 

·         No commas and blank space (white space) allowed in variable name.

·         Keywords are not used as name of the variable.

• Python also uses a variable to store the information.
• Variables can be re-declared even after you have declared it them for once.
• Declare local variable when you want to use, it for current function.
• Declare Global variable when you want to use the same variable for whole of the program.
• To delete variable it uses keyword "del".

 

Assigning Values to Variables: Python variables do not need explicit declaration to reserve memory space. The declaration happens automatically when you assign a value to a variable. The equal sign (=) is used to assign values to variables.

Total  =  50                 # An integer assignment

Rate   = 100.0            # A floating point assignment

name    = "Jaypal"     # A string assignment

 

Multiple Assignment: Python programming language allow, you to declaration of multiple variable and its assign multiple value to the variables. 

For Example:

            X=y=z=10

Here- x , y and z are the variables with the value 10, and all three variables are assigned to the same memory location. You can also assign multiple objects to multiple variables.

            x,y,z = 25,3.5,”Ramakant”

Here,  x is integer type variable, y is float type variable  and z is string type variable, they are assigned to variables x, y and Z respectively.

For Example: Write a program demonstrate the use of variable.

a = 55  #here a is variable of integer type

b = 35

c = a + b

print("Addition of two Number is=",c)

welcome = "Welcome"   #here welcome is string variable

aryan = " Aryan Computers,Barshi"

welcome = welcome + " to " + aryan

print(welcome)

Output:

 

 

How you cast one variable type into another. Most of the other variable types you typically would not want to cast to.  These are following a few of the important variable types in Python-

 int(variable) - casts variable to integer

 str(variable) - casts variable to string

 float(variable) - casts variable to float (number with decimal)