C# Validate the first two digits for a four digit console input

Question

I'm trying to validate input from a console input

The requirement is for the first 2 digits of the console input to be 20

I think

input[0] = '2' will validate that the first digit is a 2

What would the syntax for validating 20 be?

Thanks.

You need to try yourself first, if you can't do that then do google for simple questions... — mmushtaq, Aug 05 '16 at 05:19
Thanks for the reply. Is there any way to combine the two inputs as in maybe input[0,1] == '20' ? — Noel ST, Aug 05 '16 at 06:01

Jonesopolis · Accepted Answer · 2016-08-05T05:16:49.643

3

Many ways to accomplish this, but I'd go with string method StartsWith:

var input = Console.ReadLine();

if(input.StartsWith("20"))
{

}

StartsWith will not throw if input is less than 2 characters, and Console.ReadLine (assuming that's what you are using) will, in all common user scenarios, not return null.

edited Aug 05 '16 at 05:16

answered Aug 05 '16 at 05:11

Jonesopolis

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Mostafiz · Answer 2 · 2016-08-05T05:13:57.813

0

You can do it by

private static void Main(string[] args)
        {

        string s = Console.ReadLine();

        if (s.Length >= 2 && s.Substring(0, 2) == "20")
        {
            Console.WriteLine("Yes");
        }
        else
        {
            Console.WriteLine("No");
        }

        Console.ReadKey();
    }

edited Aug 05 '16 at 05:13

answered Aug 05 '16 at 05:10

Mostafiz

7,243
3
28
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1

This would throw an exception if the input were less than two characters long. – Wasabi Fan Aug 05 '16 at 05:12

score 0 · Answer 3 · answered Aug 05 '16 at 05:12

0

if(input.StartWith("20") && input.Length >= 2)
{
   Console.WriteLine("Valid Input");
}
else
{
   Console.WriteLine("Not Valid");
}

answered Aug 05 '16 at 05:12

Lakhtey

35
1
13

1

Please add some description as to why this code answers the question posed. – Will Ray Aug 05 '16 at 06:06

C# Validate the first two digits for a four digit console input

3 Answers3