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c#validationparameter-passing
Simcha Bryzgalov
Simcha Bryzgalov

Reputation: 13

C# Pass criteria of input validation as parameter

I have simple function of input validation:

private static int GetInt()
{
    int tryInt;

    while (true)
    {
        if (int.TryParse(Console.ReadLine(), out tryInt)) 
            return tryInt;
        else 
            Console.Write("Try again:");
    }
}

I want to pass in criteria (let's say I want odd numbers, more than 20) How can I do it? Should I?

private static int GetInt(< criteria >)
{
    int tryInt;

    while (true)
    {
        if (int.TryParse(Console.ReadLine(), out tryInt) && < criteria >) 
           return tryInt;
        else 
           Console.Write("Try again:");
    }
}

Upvotes: 1

Views: 51

Answers (2)

Karen Payne
Karen Payne

Reputation: 5102

An elegant solution is using Spectre.Console NuGet package, using Text prompt which as shown accepts an int with, in this case validates the value entered is an int and the value entered here is between 1 and 10. Also uses colors to are optional.

Code written using NET 9.

internal class Prompts
{
    public static int GetInt(string title = "Enter a number") =>
        AnsiConsole.Prompt(
            new TextPrompt<int>($"[yellow]{title}[/]?")
                .PromptStyle("cyan")
                .Validate(ValidateBetweenOneAndTen)
                .ValidationErrorMessage("[red]Must be an integer[/]"));

    private static ValidationResult ValidateBetweenOneAndTen(int value) =>
        value is >= 1 and <= 10 ? 
            ValidationResult.Success() : 
            ValidationResult.Error("Must be between 1 and 10");
}

Usage:

internal partial class Program
{
    static void Main(string[] args)
    {

        var number = Prompts.GetInt();
        Console.Clear();
        AnsiConsole.MarkupLine($"[bold]You entered[/]: [yellow]{number}[/]");
        Console.ReadLine();
    }
}

Upvotes: 1

Sergey Sosunov
Sergey Sosunov

Reputation: 4600

Sounds like you can utilize Func delegates

Example:

using System;

public class Program
{
    public static void Main()
    {
        int number = GetInt();
        Console.WriteLine($"You entered: {number}");
        
        int number2 = GetInt(n => n > 0 && n < 100);
        Console.WriteLine($"You entered: {number2}");
        
        Func<int, bool> isPositiveCriteria = number => number > 0;
        int number3 = GetInt(isPositiveCriteria);
        Console.WriteLine($"You entered: {number3}");
    }

    private static int GetInt(Func<int, bool>? additionalValidation = null)
    {
        int tryInt;
        while (true)
        {
            Console.Write("Enter a number: ");
            if (int.TryParse(Console.ReadLine(), out tryInt) && (additionalValidation == null || additionalValidation(tryInt)))
            {
                return tryInt;
            }

            Console.WriteLine("Invalid input. Try again:");
        }
    }
}

Dotnet fiddle playground

Upvotes: 2

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