正则表达式和 While 循环 - 为真时仍显示为假

Question

我正在尝试进行 while 循环以确保员工的格式正确 - 但是只有当我第一次正确输入员工 ID 时它才有效。

When I put first a wrong format to the ID and then put a correct one it does not revaluate and identify it as true

Here is the part of the code in question:

Console.Write("Please enter your employee ID:");
empID = Console.ReadLine();

string pattern = @"^\d{9}[A-Z]{1}$";

Match match = Regex.Match(empID, pattern);

while (match.Success != true)
{

    if (match.Success == true)
    {
        Console.WriteLine(empID);
    }
    else
    {
        Console.WriteLine("Incorrect employee ID - please try again");
        empID = Console.ReadLine();

    }
}

Any idea what it could be that it does not see empID as correct when entered correctly second time?

Thanks

Answer 1

You don't update match variable value in the loop. Please see my comments in the code

// here you receive your employee id
Console.Write("Please enter your employee ID:"); empID = Console.ReadLine();

string pattern = @"^\d{9}[A-Z]{1}$";

// here you initialize your match variable by result of matching with regex
Match match = Regex.Match(empID, pattern);

while (match.Success != true)
{
    if (match.Success == true)
    {
        Console.WriteLine(empID);
    }
    else
    {
        Console.WriteLine("Incorrect employee ID - please try again");

        // here you read your new employee id, but match variable is not updated
        empID = Console.ReadLine();

        // this is what you missed
        match = Regex.Match(empID, pattern);
    }
}