using a for loop to iterate through a dictionary

Question

I generally use a foreach loop to iterate through Dictionary.

Dictionary dictSummary = new Dictionary();
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Answer 1

You don't need to use .ToArray() or .ElementAt(). It is as simple as accessing the dictionary with the key:

dictSummary.Keys.ToList().ForEach(k => dictSummary[k] = dictSummary[k].Trim());

Answer 2

KeyValuePair<TKey, TValue> doesn't allow you to set the Value, it is immutable.

You will have to do it like this:

foreach(var kvp in dictSummary.ToArray())
    dictSummary[kvp.Key] = kvp.Value.Trim();

The important part here is the ToArray. That will copy the Dictionary into an array, so changing the dictionary inside the foreach will not throw an InvalidOperationException.

An alternative approach would use LINQ's ToDictionary method:

dictSummary = dictSummary.ToDictionary(x => x.Key, x => x.Value.Trim());

Answer 3

what about this?

for (int i = dictSummary.Count - 1; i >= 0; i--) {
  var item = dictSummary.ElementAt(i);
  var itemKey = item.Key;
  var itemValue = item.Value;
}