C＃爲什麼我得到「未處理的異常：System.FormatException：輸入字符串的格式不正確。」當我使用TryParse？

Question

我得到「未處理的異常：System.FormatException：輸入字符串的格式不正確。」但實際上我用TryParse捕獲了Exception。

using System; 
using System.Linq; 
using System.Collections.Generic; 

class MinAndMax 
{ 
    static void Main() 
    { 
     // Task 3 - Write a program that reads from the console 
     // a sequence of N integer numbers and returns the minimal 
     // and maximal of them. 

     int n; 
     double num = 0, counter = 0, minNum = 0, maxNum = 0; 
     List<double> numbers = new List<double>(); 

     Console.Write("How many numbers will you enter: "); 
     bool isNum = int.TryParse(Console.ReadLine(), out n); 

     if (isNum) 
     { 
      for (counter = 1; counter <= n; counter++) 
      { 
       Console.Write("Enter number {}: ", counter); 
       bool isValid = double.TryParse(Console.ReadLine(), out num); 

       if (isValid == false) 
       { 
        Console.WriteLine("Invalid input!"); 
       } 
       else 
       { 
        numbers.Add(num); 
       } 
     } 

     minNum = numbers.Max(); 
     maxNum = numbers.Min(); 

     Console.WriteLine("The maximal of the numbers is: " + maxNum); 
     Console.WriteLine("The minimal of the numbers is: " + minNum); 
     } 
     else 
     { 
      Console.WriteLine("Invalid input!"); 
     } 
    } 
} 

當輸入字符串它進入else塊（所以它捕獲該異常），但是當輸入是一個整數，我得到未處理的異常：System.FormatException：輸入字符串的不正確的格式。

Answer 1

線

Console.Write("Enter number {}: ", counter); 

將拋出一個異常，則應該將其更改爲

Console.Write("Enter number {0}: ", counter); 

Answer 2

這是導致該錯誤消息的格式字符串。把括號之間的索引：

Console.Write("Enter number {0}: ", counter); 

Answer 3

除了已經由以前的海報固定Console.Write錯誤，你也將獲得一個System.InvalidOperationException這裏如果用戶僅輸入字符串因爲numbers列表是空的。

minNum = numbers.Max(); 
maxNum = numbers.Min();