# C# Bindings Usage Advice

## Adding reference to the GDAL/OGR assemblies

TODO

## Using the interface classes

TODO

## Modifying Local Search Path

If you want to add a folder to PATH during run-time, so you don’t have to pollute system PATH permanently, you can do it this way, in C#

    using System.Runtime.InteropServices;

    ...

    [DllImport("kernel32.dll", CharSet=CharSet.Auto, SetLastError=true)]
    public static extern bool
    SetEnvironmentVariable(string lpName, string lpValue);

    ...

    string GDAL_HOME = @";C:\Program Files\FWTools\bin";  // for example

    string path = Environment.GetEnvironmentVariable("PATH");
    path += ";" + GDAL_HOME;
    SetEnvironmentVariable("PATH", path);

MSDN documentation:

- http://msdn2.microsoft.com/en-us/library/ms686206.aspx

- http://msdn2.microsoft.com/en-us/library/system.environment.setenvironmentvariable.aspx

Instead of the P/Invoke call to SetEnvironmentVariable(), you can use C# native method Environment.SetEnvironmentVariable(). Read the doc carefully, because there are two versions of this method. Unlike the Win32 API call accessed through P/Invoke, the method Environment.SetEnvironmentVariable() has an overload that may change environment permanently, across processes.