Get the last N characters from a string

Question

I have a string which in reality is a phone number. But a phone number can have some formats like:

[phone]

34 989898

989898

The constant is that always the last 8 numbers are the phone numbers, I wonder how I separate these last 8 numbers from the rest. Example:

numero = "[phone]"

Turn

n1 = "+55 34 ";
n2 = "98989898";

Could use the Substring? And how?

Answer 1

The constant is that always the last 8 numbers are the numbers of the phone, I wonder how I separate these last 8 numbers from the remainder.

Use the Substring using as parameter the size of your variable less the number of characters you want to capture.

Remember before checking if the size of the string contains the amount of characters desired.

public class Program
{
    public static void Main()
    {
        var telefone = "123 12345678";
        Console.WriteLine(telefone);        
        if(telefone.Length > 8) 
               Console.WriteLine(telefone.Substring(telefone.Length -8)); //12345678
    }
}

Code in. net FIDDLE https://dotnetfiddle.net/CMAnYN

number = "[phone]"

Turn n1 = "+55 34 "; N2 = "989898";

If your variable always contains this format, you can use the method Split using space as a parameter:

public static void Main()
    {
        var telefone = "[phone]";
        Console.WriteLine(telefone);    

        var telefoneSeparado = telefone.Split(' ');

        Console.WriteLine("CD País: " + telefoneSeparado[0]); //+55     
        Console.WriteLine("DDD: " + telefoneSeparado[1]); //81      
        Console.WriteLine("Número: " + telefoneSeparado[2]); //12345678
    }

Code in. net FIDDLE: https://dotnetfiddle.net/4qHIJM

If your variable does not have a specific format, you can use the method String.Remove works in a similar way to String.Substring

public static void Main()
    {
        var telefone = "[phone]";
        Console.WriteLine(telefone); //[phone]      

        Console.WriteLine(telefone.Substring(telefone.Length -8)); //2345678

        Console.WriteLine(telefone.Remove(telefone.Length - 8)); //+55 81 

    }

Code working on . NET Fiddle https://dotnetfiddle.net/Hna8yD

Answer 2

I like the regular expression approach.

var regex = new Regex(@"([\d]{8})");
var match = regex.Match("[phone]");
if (match.Success)
{
    Console.WriteLine(match.Value); // Imprime "98989898"
}

Answer 3

If it’s in that format:

string telefone = "[phone]";

Console.WriteLine(telefone.Substring(telefone.Length - 8));

Link to the Demo