I’m applying for a mid level devloper position.

In order to progress to 2nd interview, you need to pass a technical test. One of the questions was to write a function to work out linux based octal file permissions.

How would yuou guys improve it and tell me why your way is better

using System; using System.Collections; using System.Linq;  public class ReadWriteExecute {     public static int CalculatePermissionSum(string permString)     {         int octalPerm = 0;          foreach (char permission in permString.ToArray())         {             switch (permission)             {                 case 'r':                     octalPerm += 4;                     break;                 case 'w':                     octalPerm += 2;                     break;                 case 'x':                     octalPerm += 1;                     break;                 case '-':                     octalPerm += 0;                     break;             }         }         return octalPerm;     }      public static string SymbolicToOctal(string permString)     {         string octalPerm = string.Empty;               for(int x=0; x<=6;x+=3)         {              octalPerm += CalculatePermissionSum(new string(permString.Skip(x).Take(3).ToArray())).ToString();         }         return octalPerm;     }      public static void Main(string[] args)     {         // Should write 752         Console.WriteLine(ReadWriteExecute.SymbolicToOctal("rwx-x--r-"));     } }