Get the last N characters of a string

If it's in this format:

string telefone = "+55 34 98989898";

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

Demo Link

  

The constant is that always the last 8 numbers are the numbers of the   phone, I wanted to know how I separate these last 8 numbers from the   remaining.

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

Remember before checking that the size of string contains the desired number of characters.

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
    }
}

FIDDLE net code link

  

number="+55 34 98989898"

     

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

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

public static void Main()
    {
        var telefone = "+55 81 12345678";
        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
    }

FIDDLE .net code: link

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

public static void Main()
    {
        var telefone = "+55 81 12345678";
        Console.WriteLine(telefone); //+55 81 12345678      

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

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

    }

Code working in .NET Fiddle link

I like the regular expression approach.

var regex = new Regex(@"([\d]{8})");
var match = regex.Match("+55 34 98989898");
if (match.Success)
{
    Console.WriteLine(match.Value); // Imprime "98989898"
}