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iterating through collections

I Googled this today – it explained nicely a problem I was having, and got me to start thinking about the differences between a loop that reads:

MyObject obj = null; for (int i = 0; i < someCounter; i++) {     obj = MyObjectCollection[i];     obj.Foo(); }

as opposed to this:

foreach(MyObject o in MyObjectCollection) {     o.Foo(); }

I’d always suspected that there were likely overhead/performance problems with the foreach/in statement, but damn is it convenient. I’d never suspected that the loop used a fundamentally different mechanism to achieve that ease of use. What I found interesting is that while the author of the referenced blog entry took home the lesson that ‘mutable value types’ == potentially harmful, the lesson I got was ‘foreach/in’ == potentially harmful. I agree that structs that act more like classes should probably be classes – on the other hand, if you can’t predict what is going to come out of a statement shouldn’t that be viewed as the problem?

(And I’m going to have to find an addition to my css in order to format code snippets better…)

[Update 11/12/2004: found it! Right here; prettified the code, though I’m not too sure about the absolutely stark-white background. It’ll stay that way for now]

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