#1,120 – The Iteration Variable in a foreach Loop Is Read-Only

Unlike the for loop, the iteration variable in a foreach loop is read-only.  Attempting to assign a value to the variable within the body of the loop will result in a compile-time error.

            string[] dogs = {"Kirby", "Jack", "Ruby", "Lassie"};

            // for loop allows writing to iteration variable
            Console.WriteLine("= for loop");
            for (int i = 0; i < dogs.Length; i++)
            {
                Console.WriteLine(dogs[i]);
                if (dogs[i].StartsWith("J"))
                    i++;  // skip next
            }

            Console.WriteLine("= foreach loop");
            foreach (string s in dogs)
            {
                if (s.StartsWith("J"))
                    s = "****";     // ERROR
                Console.WriteLine(s);
            }

1120-001

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About Sean
Software developer in the Twin Cities area, passionate about .NET technologies. Equally passionate about my own personal projects related to family history and preservation of family stories and photos.

One Response to #1,120 – The Iteration Variable in a foreach Loop Is Read-Only

  1. Pingback: Dew Drop – June 19, 2014 (#1800) | Morning Dew

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