C# SDK

// NuGet Install
// Install-Package OpenAI

using OpenAI;
using OpenAI.Chat;

class Program
{
    static async Task Main(string[] args)
    {
        var apiKey = Environment.GetEnvironmentVariable("API_KEY");
        var client = new OpenAIClient(apiKey);
        
        var chatClient = client.GetChatClient("gpt-4o");
        
        var messages = new List<ChatMessage>
        {
            new UserChatMessage("Hello, AI!")
        };
        
        var response = await chatClient.CompleteChatAsync(messages);
        
        Console.WriteLine(response.Value.Choices[0].Message.Content);
    }
}