C＃循环直到给出有效答案

Question

I'm trying to make a text adventure type game, and I am very new to C#. I've searched the web for about half an hour and found nothing that has worked. I want to make something that will not continue until a valid answer is input

This is an example:

var answer3 = Console.ReadLine();

if (answer3.Equals("1"))
{
   Console.WriteLine("ans 1");
}
else if (answer3.Equals("2"))
{
   Console.WriteLine("Ans 2");
}
else
{
   Console.WriteLine("Answer decision 1,2, or 3"); //This is what I need repeated

Answer 1

do{

    var answer3 = Console.ReadLine();


}while(answer3 != "something" || answer3 != "something else");

|| means 'or'

do- while basically executes something at least once, until some condition is true, the while.

do{

 this

}while(this isn't true);

Answer 2

You can use a while loop

string answer = Console.ReadLine();
while(!String.Equals(answer, desiredAnswer)
{
  Console.WriteLine("Answer decision 1,2, or 3");
  answer = Console.ReadLine();  
}

If you have multiple desired answers, you can just OR them in the while condition

Answer 3

One way to do it that is very C#/.Net is to use Lambda expressions. You define the list of valid values in an array and it will loop until you get one of these values.

string myString = "";
string[] validValues = new string[] { "1", "2", "3" };
while (!validValues.Any(myString.Equals))
    myString = Console.ReadLine();

It is equivalent to:

string myString = "";
string[] validValues = new string[] { "1", "2", "3" };
while (!validValues.Any(s=>myString.Equals(s))
    myString = Console.ReadLine();

switch (myString)
{
    case "1":
        Console.WriteLine("ans 1");
        break;
    case "2":
        Console.WriteLine("ans 2");
        break;
    case "3":
        Console.WriteLine("ans 3");
        break;
 }

validValues.Any will return true if the condition in brackets pass on any element. The Lambda expression s=>myString.Equals(s) is almost like a function that will return true when the argument s is equal to myString. s will be replaced by each element of the list when using Any .

In this case it is important to notice that => does not mean greater or equal. It means that you defined a function/expression that takes s as parameter and returns myString.Equals(s) . Then you pass it to Any , which will apply it on every element until one returns true . If none returned true, Any will return false .

Lambda expressions are a very neat feature of C#, when you will get used to it, it will allow you to write code which is much simpler than in languages like C++. Since most of us spend alot of time writing boilerplate code or manipulating data obtained from various sources it can make our life alot easier.

More on lambda expressions