Prompting User for valid Input in Console Application

In a console apps, there is often a need to obtain user input from the console while ensuring that the input is not empty or only whitespace characters.

In this sample, we define a method GetUserInput that takes an optional message parameter. It continuously prompts the user until a non-empty, non-whitespace input is provided.

static string GetUserInput(string message = "Please enter some input:")
{
    string input;
    do
    {
        Console.WriteLine(message);
        input = Console.ReadLine()?.Trim();
    } while (string.IsNullOrWhiteSpace(input));
    return input;
}

Explanation:

• message parameter allows customizing input prompt message.
• Console.ReadLine()?.Trim() reads user input and trims leading/trailing whitespace.
• The ?. operator is used for null-conditional access, ensuring that Console.ReadLine() doesn't throw a null reference exception if the input is null.
• do-while loop ensures user input is not empty or whitespace.