c# - 在触发方法 c# 之前需要验证一组用户输入

Question

在触发我的方法并将数据存储到我的数据库之前，我需要从我的控制台应用程序检查一组用户输入。

程序无一异常(exception)地编译和运行。但如果有一个输入错误，其他三个输入仍然会通过。
虽然，我真正需要的是在触发该方法之前确保 4 个用户的输入正确，如果只有一个输入错误，则整个程序应该停止并退出。

using System;
using System.Threading;

namespace BarcodeValidation
{
    class Program
    {
        static void Main(string[] args)
        {
            ReadBarcode();
        }

        static void ReadBarcode()
        {
            var barcodes = GetInput();

            foreach (var item in barcodes)
            {
                // something
                CheckUserInput(item);
            }
        }

        static string[] GetInput()
        {
            Console.WriteLine("Please enter 4 products ID, Barcodes, MPN or EAN code:");

            string[] barcode = new string[4];

            for (int i = 0; i < barcode.Length; i++)
            {
                barcode[i] = Console.ReadLine();
            }
            return barcode;
        } // end of method here

        static void CheckUserInput(string userInput)
        {
            int msec = 5000;

            try
            {
                if (!(userInput == "F5121" || userInput == "F3111" || userInput == "F8331" || userInput == "F5321"))
                {
                    Console.WriteLine("Enter a valid MPN codes for your products");
                    Thread.Sleep(msec);
                    Environment.Exit(0);
                }
                else
                {
                    switch (userInput)
                    {
                        case "F5121":
                            Console.WriteLine("barcode 1 is =", userInput);
                            Thread.Sleep(msec);
                            break;
                        case "F3111":
                            Console.WriteLine("barcode 2 is =", userInput);
                            Thread.Sleep(msec);
                            break;
                        case "F8331":
                            Console.WriteLine("barcode 3 is =", userInput);
                            Thread.Sleep(msec);
                            break;
                        case "F5321":
                            Console.WriteLine("barcode 4 is =", userInput);
                            break;
                    }
                }
            }
            catch (Exception ex)
            {
                Console.WriteLine(ex.Message);
            }
        }
    }
}     

Answer 1

因为您有一个实际测试用户输入的方法使用它的返回值:

static bool CheckUserInput(string userInput) // true : valid | false : invalid
{
    int msec = 5000;
    try
    {
        if (!(userInput == "F5121" || 
              userInput == "F3111" || 
              userInput == "F8331" || 
              userInput == "F5321"))
        {     
            Console.WriteLine("Enter a valid MPN codes for your products");
            return false;
        }
        else
        {
            switch (userInput)
            {
                case "F5121":
                    Console.WriteLine("barcode 1 is =", userInput);
                    Thread.Sleep(msec);
                    return true;                      
                case "F3111":
                    Console.WriteLine("barcode 2 is =", userInput);
                    Thread.Sleep(msec);
                    return true;
                case "F8331":
                    Console.WriteLine("barcode 3 is =", userInput);
                    Thread.Sleep(msec);
                    return true;
                case "F5321":
                    Console.WriteLine("barcode 4 is =", userInput);
                    return true;
                default:
                    return false;
            }
        }

    }
    catch (Exception ex)
    {

        Console.WriteLine(ex.Message);
        return false;
    }

} 

ReadBarcodes 可能看起来像这样:

static void ReadBarcode()
{
    var barcodes = GetInput();
    bool errorOccured = false;
    foreach (var item in barcodes)
    {
        // something
        if(!CheckUserInput(item))
        {
            errorOccured = true; // keep track of that error
            break; //Break for if 1 input is invalid
        }
    }
    //Further execution....
    if(errorOccured)
    {
        return; //Do not continue ...
    }
    //Do other things you want to do. Your input is valid at this point !
}

或更短如默认引用:

static void ReadBarcode()
{        
    if(!GetInput().All(CheckUserInput))
    {
        return;
    }
    //Your stuff goes here. Input is valid at this point
}