Variable and constant in python programming are two important concepts that allow us to store and manipulate data. In this blog post, we will take a look at what variables and constants are, how to use them in Python, and the differences between them.
What are variables in Python?
In Python, a variable is a storage location that is used to hold a value. The value of a variable can be changed at any time during the execution of a program.
To declare a variable in Python, you simply need to specify the name of the variable and assign it a value using the assignment operator (=).
message = "Hello, World!" print(message) # Output: "Hello, World!" message = "Goodbye, World!" print(message) # Output: "Goodbye, World!"
In the example above, we declare a variable called message and assign it the value “Hello, World!”. We then print the value of the variable to the console. Next, we change the value of the message variable to “Goodbye, World!” and print it again. As you can see, the value of a variable can be changed at any time.
It is important to note that Python is a dynamically-typed language, which means that the type of a variable (e.g., string, integer, etc.) is determined at runtime based on the value that is assigned to it.
x = 10 # x is an integer y = "Hello" # y is a string
What are constants in Python?
Constants are similar to variables in that they are used to store values, but the values of constants cannot be changed once they are set. In Python, there is no built-in syntax for declaring constants, but it is a common practice to use all capital letters and underscores for the names of constants to differentiate them from variables.
PI = 3.14159 # PI is a constant GRAVITY = 9.81 # GRAVITY is a constant
It is important to note that, while it is not possible to change the values of constants directly, it is still possible to modify the values of objects that are stored in constants. For example:
MY_LIST = [1, 2, 3] # MY_LIST is a constant MY_LIST.append(4) # This is allowed print(MY_LIST) # Output: [1, 2, 3, 4] MY_LIST = [5, 6, 7] # This will cause an error
In the example above, we declare a constant called ‘MY_LIST‘ and assign it a list of values. We are able to modify the list by adding an element to it, but if we try to reassign a new value to the ‘MY_LIST‘ constant, we will get an error.
Differences between variables and constants
There are a few key differences between variables and constants in Python:
- The values of variables can be changed at any time, while the values of constants cannot be changed once they are set.
- There is no built-in syntax for declaring constants in Python, but it is a common practice to use all capital letters and underscores for the names of constants.
- The values of variables can be any type (e.g., string, integer, etc.), while the values of constants are typically