Environment variables are essential components in any operating system, including Windows. They are used to store system-wide values that can be referenced by applications and scripts to determine the environment in which they are running. The SetEnvironmentVariable function is a key method for setting these variables programmatically. This article will explore how to use SetEnvironmentVariable in Windows, its importance, and provide practical examples for both Command Prompt (CMD) and PowerShell.

Examples:

Using Command Prompt (CMD)

In Windows, you can set environment variables using the setx command in Command Prompt. Here’s how you can set a new environment variable named MY_VARIABLE with the value HelloWorld.

1. Open Command Prompt as an Administrator.
2. Run the following command:

   setx MY_VARIABLE HelloWorld

To verify that the environment variable has been set, you can use the echo command:

   echo %MY_VARIABLE%

Using PowerShell

PowerShell provides a more flexible and powerful way to manage environment variables. Here’s how you can set an environment variable in PowerShell:

1. Open PowerShell as an Administrator.
2. Run the following command:

   [System.Environment]::SetEnvironmentVariable('MY_VARIABLE', 'HelloWorld', 'User')

To verify that the environment variable has been set, you can use the following command:

   echo $env:MY_VARIABLE

Using C# in a .NET Application

If you are developing a .NET application and need to set environment variables programmatically, you can use the SetEnvironmentVariable method from the System.Environment class. Here’s an example in C#:

using System;



class Program

{

    static void Main()

    {

        Environment.SetEnvironmentVariable("MY_VARIABLE", "HelloWorld", EnvironmentVariableTarget.User);

        Console.WriteLine("Environment variable set successfully.");

    }

}

Using Batch Script

You can also set environment variables within a batch script. Here’s an example:

@echo off

set MY_VARIABLE=HelloWorld

echo %MY_VARIABLE%

Save the above script as setenv.bat and run it to set the environment variable.