#CLUB5050 PYTHON TUTORIAL - USE OF VARIABLES IN PROGRAMMING

Good day everyone, I greet you all. Today I want to teach you the use of variables in programming. So if you are ready to learn with me, tighten your belt let's dive in...

VARIABLES IN PROGRAMMING

When we ask a computer to perform an operation for us, we usually need to store values and give them names so that we can refer to them later. This is where variables come in handy. Variables are names that we give to certain values in our programs. Those values can be of any data type; numbers, strings or even the results of operations. We already used variables in some of our initial examples like using them to store a name or a value. Now we are going to learn exactly how they work and how to make the most of them. Think of variables as containers for data. When you create a variable in your code, your computer reserves a chunk of its own memory to store that value.

This lets the computer access the variable later to read or modify the value. Let's see this in action. Imagine a simple script that calculates the area of a rectangle using the formula area equals length times width. Area, length and width can all be represented by variables like this. In this script we are creating three variables and storing different values in each. The process of storing a value inside a variable is called assignment. Here we assign the length variable the value of 10. We assign the width variable the value of 2 and we assign the area variable with the result of the expression length times width. An expression is a combination of numbers, symbols or other variables that produce a result when evaluated.

The result of Length x Width is stored in the Variable, Area

In the example above, we are multiplying the value of two variables to arrive at the value that we want. Finally, we use our old friend the print function to display the value of the area on the screen.

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The result of the calculation (Area) shown in the output terminal

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All right. We have just seen how to assign values to variables, use expressions to calculate more complex values and then print the contents of a variable. Variables are important in programming because they let you perform operations on data that may change. For example, if we extended our rectangle script to accept any input as the value of the length and width variables, we could calculate the area of a rectangle of any size or to give a more IT focused example, say we have a script that performs a specific operation on a file. We can extend that script to perform the same operation on any file but only if the program used a variable to store the file name. You might have noticed that we assign a value to a variable by using the equal sign in the form of variable equals value.

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Variable Names

Generally, you can name variables whatever you like but there are some restrictions. First, you shouldn't use as variable names any of the key words or functions that Python reserves for its own, like print. Using these reserved terms will make your program confusing to read and will result in errors. Python also has some restrictions on the characters you can use to define a variable. Variable names can't have any spaces and they must start with either a letter or an underscore. Also, they can only be made up of letters, numbers and underscores. Let's check out some examples of valid and invalid variable names to understand this better.

• This_is_a_python_tutorial
  The above variable is a valid Variable name.

• This_is_a_python_tutorial2 is also a valid variable name.

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1_is_a_number is an invalid variable name because variable names must start with a letter or underscore.

Apples_&_oranges is invalid because it uses the special character Ampersand.

Finally, remember that precision is important when programming. Python variables are case sensitive, so capitalization matters. Lowercase name, uppercase name and all caps name are all valid and different variable names, and that rule on variables is invariable.

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Thanks for reading till the end, I believe that you have learnt something new today

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