Basic Console Apps C#

Compiling and Executing Programs Terminology

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• Entry Point: Code (usually a method) that's automatically run when a program is launched. In C#, this method is called Main().

Overview & Examples

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Setup

Basic boilerplate setup for every C# program:

SomeFileName.csproj

<Project Sdk="Microsoft.NET.Sdk">

    <PropertyGroup>
        <OutputType>Exe</OutputType>
        <TargetFramework>net5.0</TargetFramework>
    </PropertyGroup>

</Project>

SomeFileName.cs

using System;

class Program
{
  static void Main()
  {
    // program code goes here
  }
}

Running Programs

• We run a program with the following two steps:
  • Compiling: In the project directory, run > dotnet build. FileName.cs should be the name of the file containing program code. This creates an .exe file.
  • Executing: After compiling, run the following to launch the .dll file: > dotnet run.

General Guidelines

• Files with .cs extensions contain code written by the developer.
• Files with .csproj extensions contain project configuration data.

AOT Versus JIT Compiling Overview

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• In modern programming languages, source code must be translated into machine code before computers can understand it. Some languages and platforms do this automatically, but others like C# must be explicitly compiled.

Terminology

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• Compiling: Translating one type of code into another type. Generally this refers to translating a more human-readable type of code into a more complex type of code meant only for computers.
• Just in Time: When code is compiled as a user interacts with it, as is the case with JavaScript.
• Ahead of Time: When code is compiled ahead of time, as is the case with C#.

Sample .csproj code:

DoubleIt.csproj

<Project Sdk="Microsoft.NET.Sdk">

    <PropertyGroup>
        <OutputType>Exe</OutputType>
        <TargetFramework>net5.0</TargetFramework>
    </PropertyGroup>

</Project>

• Build a C# program with the following command: dotnet build.
• Run a C# program with the following command: dotnet run.
• The Console.WriteLine() method prints a string to the console.
• The Console.ReadLine() method is used to retrieve input the user has typed into the command line.

Dotnet Watcher Terminology

Watcher: Monitors files so we don't need to constantly type dotnet run. Here's how we add a watcher:

dotnet watch run

We can also do this with the build command:

dotnet watch build