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POWhy is The Iteration Variable in a C# foreach statement read-only?
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copied!<p>As I understand it, C#'s foreach iteration variable is immutable.</p> <p>Which means I can't modify the iterator like this:</p> <pre><code>foreach (Position Location in Map) { //We want to fudge the position to hide the exact coordinates Location = Location + Random(); //Compiler Error Plot(Location); } </code></pre> <p>I can't modify the iterator variable directly and instead, I have to use a for loop</p> <pre><code>for (int i = 0; i < Map.Count; i++) { Position Location = Map[i]; Location = Location + Random(); Plot(Location); i = Location; } </code></pre> <p>Coming from a C++ background, I see foreach as an alternative to the for loop. But with the above restriction, I usually fallback to using the for loop. </p> <p>I'm curious, what is the rationale behind making the iterator immutable? </p> <hr> <p>Edit: </p> <p>This question is more of a curiousity question and not as a coding question. I appreciated the coding answers but I can't mark them as answers.</p> <p>Also, the example above was over-simplified. Here is a C++ example of what I want to do:</p> <pre><code>// The game's rules: // - The "Laser Of Death (tm)" moves around the game board from the // start area (index 0) until the end area (index BoardSize) // - If the Laser hits a teleporter, destroy that teleporter on the // board and move the Laser to the square where the teleporter // points to // - If the Laser hits a player, deal 15 damage and stop the laser. for (int i = 0; i < BoardSize; i++) { if (GetItem(Board[i]) == Teleporter) { TeleportSquare = GetTeleportSquare(Board[i]); SetItem(Board[i], FreeSpace); i = TeleportSquare; } if (GetItem(Board[i]) == Player) { Player.Life -= 15; break; } } </code></pre> <p>I can't do the above in C#'s foreach because the iterator i is immutable. I think (correct me if I'm wrong), this is specific to the design of foreach in languages.</p> <p>I'm interested in why the foreach iterator is immutable.</p>

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