.NET by Roman

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;
        input = Console.ReadLine()?.Trim();
    } while (string.IsNullOrWhiteSpace(input));
    return input;


  • 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.


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