NP80 compared with -1

Thank you for your explanation, Alan.

s.IndexOf("ever") always returns -1 because "ever" is not contained within any of the strings in the arrBookTitles array.

Consequently, the variable 'ever' is never incremented and remains at its original value of 0.

I altered the above program for better understanding. According to the above explanation out put of the altered program must be -1 but program is producing 0. Please explain the reason.

using System;

class Foreach

{

   // Digging into an array using foreach.

   public static int Main(string[] args)

   {

      string[] arrBookTitles = new string[] { "aaa", "www", "rrr", "xxx" };

      int ever = 0;

      foreach (string s in arrBookTitles)

      {

         if (-1 != s.IndexOf("ever"))

            ever++;

      }

      Console.WriteLine(ever);

      return 0;

   }

}

/*

0

*/

The s.IndexOf(t) method returns the index (starting from 0) of the first occurrence of the string 't' within the string 's'.

So, if   s  ==  "never" and  t  ==  "ever", the method would return 1.

If 't' cannot be found, then the method returns a value of -1.

So, in this line:

if (-1 != s.IndexOf("COM"))

the code within the 'if' statement is only executed if "COM" is contained within the string 's'.