Variables, Data Types and Constants in C#

1How Does C# Store Information?

Hi friends, in this article we will learn about variables, data types and constants in C#. Whenever an application stores a name, age, price or login status, it needs a place to keep that information. A variable is a named storage location. A data type defines what kind of value it can hold. A constant stores a value that cannot change. We use them in almost every C# application.

2Think About a Shopping App

Imagine you are building an online shopping application. You need to store a customer's name, the number of items in the cart, the total bill and whether payment is completed.

The customer's name is text. The item count is a whole number. The bill can contain decimal values. Payment status is either true or false.

Each value needs a suitable data type. The application can then use these values to calculate totals and display information.

3Understand These C# Building Blocks

1. Variables

A variable has a name and stores a value. You can change its value while the program runs.

int age = 30;
age = 31;

2. Common data types

3. The var keyword

var lets the compiler identify the type from the assigned value. The type is still fixed after it is determined.

var city = "Bengaluru";

4. Constants

Use const when a value must never change after declaration. A constant needs a value when you declare it.

const double TaxRate = 0.18;

4Let's Build a Shopping Summary

Now let's declare different variables and a constant. We will calculate the final amount and display the shopping details.

using System;

class Program
{
    static void Main()
    {
        string customerName = "Ravi";
        int itemCount = 3;
        decimal totalAmount = 1500.50m;
        bool isPaid = true;
        const decimal taxRate = 0.18m;

        decimal tax = totalAmount * taxRate;
        decimal finalAmount = totalAmount + tax;

        Console.WriteLine("Customer: " + customerName);
        Console.WriteLine("Items: " + itemCount);
        Console.WriteLine("Paid: " + isPaid);
        Console.WriteLine("Final Amount: " + finalAmount);
    }
}

Here, taxRate is constant. The other variables hold values used in the calculation and display.

5What Will the Program Display?

The tax is 18% of 1500.50, which is 270.09. Adding it to the original amount gives 1770.5900 when displayed as a decimal value.

Customer: Ravi
Items: 3
Paid: True
Final Amount: 1770.5900

6Watch Variables Change in VS Code

Follow how the program declares values, calculates tax and displays the final amount.

7Keep These Points in Mind

Variables store values that can change. Data types define what those values can be. Constants protect values that should remain fixed.

• Variable: A named place to store data.
• Data type: Defines the kind of data.
• Constant: A value that cannot be reassigned.

Choose the correct type and meaningful names when writing C# applications.

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