#583 – You Can’t Modify the Iterator Variable Within a foreach Loop

The iterator variable within a foreach loop is the variable that takes on the value of each item within the corresponding collection, each time through the loop.

            string[] puppets =
                {"Crow T. Robot", "Howdy Doody", "Kermit",
                 "King Friday XIII", "Lamb Chop"};

            // nextPuppet is the iterator variable
            foreach (string nextPuppet in puppets)
            {
                Console.WriteLine("Puppet: {0}", nextPuppet);
            }

If you try to modify this iterator variable within the loop, however, you’ll get a compile-time error.

foreach (string nextPuppet in puppets)
{
    nextPuppet = "(" + nextPuppet + ")";
    Console.WriteLine("Puppet: {0}", nextPuppet);
}

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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.

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