try catch块问题
问题描述：
我遇到的问题是我每次环绕（要求用户输入信息）与尝试捕捉时间，所以如果他们输入了错误的东西或推错误输入将抛出一个错误。当我把尝试捕捉它不起作用它只是结束程序。如果我离开的尝试捕捉出像它是现在和用户只需按下输入崩溃程序..try catch块问题
namespace MaxHeartRate
{
class Program
{
static void Main(string[] args)
{
// Display program instructions
DisplayInstructions();
// Collected user info
CollectUserInfo();
}
static void DisplayInstructions()
{
Console.WriteLine("************************************************");
Console.WriteLine("This program will Calculate your Max Heart Rate");
Console.WriteLine("Also your Mininum and Maximum target Heart rate");
Console.WriteLine("You will have to enter your info in when promted");
Console.WriteLine("************************************************");
return;
}
static void CollectUserInfo()
{
// Declar Variables
string firstName, lastName;
int birthYear = 0;
int currentYear = 0;
int age;
double maxHeartRate, minTargetHeartRate, maxTargetHeartRate;
try
{
// User is asked to enter info
Console.Write("Enter your first Name: ");
firstName = Console.ReadLine();
Console.Write("Enter your last name: ");
lastName = Console.ReadLine();
Console.Write("Enter the current year: ");
currentYear = int.Parse(Console.ReadLine());
Console.Write("Enter your birth year: ");
birthYear = int.Parse(Console.ReadLine());
// Find Age
age = findAge(currentYear, birthYear);
// Find Max Heart rate
maxHeartRate = findMaxHR(age);
// Find Minimum Target Heart Rate
minTargetHeartRate = findMinTHR(maxHeartRate);
// Find Maximum Target Heart Rate
maxTargetHeartRate = findMaxTHR(maxHeartRate);
// Display Information
DisplayInformation(firstName, lastName, age, maxHeartRate, minTargetHeartRate, maxTargetHeartRate);
}
catch (Exception)
{
Console.WriteLine("Invalid input. Please try again");
}
// Methods
}
static int findAge(int cYear, int bYear)
{
int age = cYear - bYear;
return age;
}
static int findMaxHR(int age)
{
int MHR = 220 - age;
return MHR;
}
static double findMinTHR(double maxHeartRate)
{
double minTHR = maxHeartRate * 0.50;
return minTHR;
}
static double findMaxTHR(double maxHeartRate)
{
double maxTHR = maxHeartRate * 0.85;
return maxTHR;
}
// Display information
static void DisplayInformation(string firstName, string lastName, int age, double maxHeartRate, double minTargetHeartRate, double maxTargetHeartRate)
{
Console.WriteLine();
Console.WriteLine("************************************************");
Console.WriteLine("Hello " + firstName + " " + lastName + " You are " + age + " Years old" +
"\n" + "\nYour Max Heart rate is " + maxHeartRate +
" BPM" + "\n" + "\nYour Minimum Target Heart rate is " + minTargetHeartRate + " BPM" +
"\n" + "\nwith a Maximum Target Heart rate of " + maxTargetHeartRate + " BPM");
Console.WriteLine("************************************************");
Console.Write("Push enter to exit");
Console.ReadKey();
}
}
}
答
首先，你要拥有的try/catch内要么定义currentYear（包括尝试和catch由于这样的编译器解释代码路径），或在声明。否则，你会在该行获得CS0165: Use of unassigned local variable 'currentYear'与age = findAge(currentYear, birthYear)
下面的代码工作：
static void CollectUserInfo()
{
// Declar Varibals
string firstName, lastName;
// We can define these here so that there isn't a compiler error.
int birthYear = 0;
int currentYear = 0;
int age;
double maxHeartRate, minTargetHeartRate, maxTargetHeartRate;
// User is asked to enter info
Console.Write("Enter your first Name: ");
firstName = Console.ReadLine();
Console.Write("Enter your last name: ");
lastName = Console.ReadLine();
try
{
Console.Write("Enter the current year: ");
currentYear = int.Parse(Console.ReadLine());
Console.Write("Enter your birth year: ");
birthYear = int.Parse(Console.ReadLine());
}
catch (Exception)
{
// The result of the error.
Console.WriteLine("Invalid input.");
CollectUserInfo();
}
// Find Age
age = findAge(currentYear, birthYear);
// Find Max Heart rate
maxHeartRate = findMaxHR(age);
// Find Minimum Target Heart Rate
minTargetHeartRate = findMinTHR(maxHeartRate);
// Find Maximum Target Heart Rate
maxTargetHeartRate = findMaxTHR(maxHeartRate);
// Display Information
DisplayInformation(firstName, lastName, age, maxHeartRate, minTargetHeartRate, maxTargetHeartRate);
// Methods
}
+0
谢谢。我现在看到我有什么错误了。我首先尝试用尝试抓住包围整个事情。然后，我确实包围了当前的年份和生日，但它抛出了错误。我看到声明变量一起引起了一个问题..感谢帮助家伙.. – Maverick
答
下面是例子，你怎么能从用户重试尝试获得有效输入：
int currentYear;
while (true)
{
var currentYearText = Console.ReadLine();
if (int.TryParse(currentYearText, out currentYear))
{
// User entered a valid integer
// Validating that integer
if (currentYear > 2000 && currentYear < 2050)
{
break;
}
}
Console.Write("Please enter valid year between 2000 and 2050");
}
如果用户输入无效数据，他会被要求尝试再次。如果用户输入有效，代码将退出循环并转到下一个语句。
如果你与周围的try-catch代码如果发生错误，将跳转到catch，所以你需要以某种方式回去再问一次。另外，你可以使用'Int.TryParse'来避免try/catch – Gusman
如果你需要try/catch的帮助，为什么不告诉我们你是如何实现它的？ – oerkelens
使用调试器通常会晃动。 –