In this article, I will be explaining how to create a simple Web Calculator using .NET Core.

What is ASP.NET Core and why do we use it?

• Easy to develop Web Pages as well as Web APIs.
• Integration of modern frameworks and development workflows.
• Easy to integrate with Azure.
• Natural dependency injection support.
• Large hosting variety, like on IIS, Apache, Docker, or self-host in your own process.
• A wide range of tools that simplifies web development.
• Multi-platform, so you may build and run on Windows, macOS, and Linux.
• Open-source and with a powerful community.

We are using a single controller with two Action Results - one for the first HttpGet and another to calculate the operation on the server side. Here is the code.
public class HomeController : Controller 
{ 
    [HttpGet] 
    public IActionResult Index() 
    { 
        return View(); 
    } 
 
    [HttpPost] 
    public IActionResult Index( Operation model ) 
    { 
        if ( model.OperationType == OperationType.Addition ) 
            model.Result = model.NumberA + model.NumberB; 
        return View( model ); 
    } 
} 

This is the View,
@model Operation 
<form asp-controller="Home" asp-action="Index" method="post" > 
    <div class="form-group"> 
        <div class="row"> 
            <label asp-for="NumberA" class="col-lg-2"></label> 
            <input type="number" asp-for="NumberA" class="col-lg-2" /> 
        </div> 
        <div class="row"> 
            <label asp-for="NumberB" class="col-lg-2"></label> 
            <input type="number" asp-for="NumberB" class="col-lg-2" /> 
        </div> 
        <div class="row"> 
            <label asp-for="OperationType" class="col-lg-2"></label> 
            <select asp-for="OperationType" class="col-lg-2" asp-items="Html.GetEnumSelectList<OperationType>()"> 
                <option selected="selected" value="">Select</option> 
            </select> 
        </div> 
        <div class="row"> 
            <label asp-for="Result" class="col-lg-2"></label> 
            <input type="number" disabled="disabled" class="col-lg-2" asp-for="Result" /> 
        </div> 
        <div class="row"> 
            <input type="submit" value="Submit" asp-action="Index" /> 
        </div> 
    </div> 
</form> 

View Result in the browser.

This is the model used in here.

public class Operation 
{ 
    [Display( Name = "First Number" )] 
    public double NumberA { get; set; } 
 
    [Display( Name = "Second Number" )] 
    public double NumberB { get; set; } 
 
    [Display( Name = "Result" )] 
    public double Result { get; set; } 
 
    [Display( Name = "Operation" )] 
    public OperationType OperationType { get; set; } 
} 

public enum OperationType 
{ 
    Addition, 
    Multiplication, 
    Division, 
    Subtraction 
} 

Right now, only addition is implemented.

You can implement multiplication, division, and subtraction as well. I will publish these methods in my next article.

Congratulations, you have successfully created your Web Calculator using .NET Core.

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