using a for loop to iterate through a dictionary

Question

I generally use a foreach loop to iterate through Dictionary.

Dictionary<string, string> dictSummary = new Dictionary<string, string>(); 

In this case I want to trim the entries of white space and the foreach loop does however not allow for this.

foreach (var kvp in dictSummary) {     kvp.Value = kvp.Value.Trim();     } 

How can I do this with a for loop?

for (int i = dictSummary.Count - 1; i >= 0; i--) { } 

Answer 1

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; } 

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());