FormatException C＃

Question

所以我目前正在學習C#編程課程，以便更新。

原來我忘記了一些重要的事情！

namespace FitnessFrog
{
class Program
{
    static void Main()
    {
        int runningTotal = 0;

        bool keepGoing = true;

        while(keepGoing)
        {

            // Prompt the user for minutes exercised
            Console.Write("Enter how many minutes you exercised or type \"quit\" to exit: ");
            string input = Console.ReadLine();

            if (input == "quit")
            {
                keepGoing = false;
            }
            else
            {
                try
                {
                    int minutes = int.Parse(input);
                    runningTotal = runningTotal + minutes;

                    if(minutes <= 0)
                    {
                       Console.WriteLine("Eh, what about actually exercising then?"); 
                        continue;
                    }
                    else if(minutes <= 10)
                    {
                        Console.WriteLine("Better than nothing, am I right?");
                    }
                    else if (minutes <= 24)
                    {
                        Console.WriteLine("Well done, keep working!");
                    }
                    else if (minutes <= 60)
                    {
                        Console.WriteLine("An hour, awesome! Take a break, ok?");
                    }
                    else if (minutes <= 80)
                    {
                        Console.WriteLine("Woah, remember to drink if you're going to exercise THAT long!");
                    }
                    else
                    {
                        Console.WriteLine("Okay, now you're just showing off!");
                    }
                    Console.WriteLine("You've exercised for " + runningTotal + " minutes");
                }
                    catch(FormatException)
                    {
                        Console.WriteLine("That is not valid input");
                        continue;
                    }




                // Repeat until the user quits
            }
        }
    }
}
}

因此，當您鍵入字符串而不是整數時，我試圖讓它說“這是無效的輸入”。

提前致謝！ <3

Answer 1

int minutes = int.Parse(input); - 你應該使用TryParse()而不是Parse()

int minutes;
bool parsed = int.TryParse(input, out minutes);
if (parsed)
{
    // your if statements
}
else
{
    Console.WriteLine("That is not valid input");
}

Answer 2

您應該使用int.TryParse代替Parse，因為它具有內部異常處理機制，並且您可以使用它的返回值（true / false）來檢查操作是否成功，為了成功轉換它將返回true，並且失敗轉換的返回值將為false

int minutes;

if(!int.TryParse(input,out minutes)
{
    Console.WriteLine("invalid input");
}
else
{
   // Proceed
}

Answer 3

如果您正在接收來自用戶的輸入，您將需要考慮實際使用Int32.TryParse()方法來確定解析是否成功：

int minutes;
// Attempt the parse here
if(Int32.TryParse(input, out minutes))
{
    // The parse was successful, your value is stored in minutes
}
else 
{
    // The parse was unsuccessful, consider re-prompting the user
}