extism/dotnet/samples/Extism.Sdk.Sample/Program.cs

using Extism.Sdk.Native;
using System.Text;

var context = new Context();
var wasm = await File.ReadAllBytesAsync("./code.wasm");
using var plugin = context.CreatePlugin(wasm, withWasi: true);

var output = Encoding.UTF8.GetString(
    plugin.CallFunction("count_vowels", Encoding.UTF8.GetBytes("Hello World!"))
);
Console.WriteLine(output); // prints {"count": 3}