Navigate through dictionary <string, int> c#

Question

What is the better way to Navigate through a dictionary ? I used to use the code below when i had IDictionary:

Assume that I have IDictionary named freq

IEnumerator enums = freq.GetEnumerator();
while (enums.MoveNext())
{
    string word = (string)enums.Key;
    int val = (int)enums.Value;
    .......... and so on

}

but now, I want to do the same thing using dictionary

Answer 1

The default enumerator from a foreach gives you a KeyValuePair<TKey, TValue> :

foreach (var item in dictionary)
// foreach (KeyValuePair<string, int> item in dictionary)
{
    var key = item.Key;
    var value = item.Value;
}

This simply compiles into code that works directly with the enumerator as in your old code.

Or you can enumerate the .Keys or .Values directly (but you only get a key or a value in that case):

foreach (var key in dictionary.Keys)

foreach (var val in dictionary.Values)

And or course linq works against dictionaries:

C# linq in Dictionary<>

Answer 2

Well you could do the same thing with Dictionary , but it would be cleaner to use foreach in both cases:

foreach (var entry in dictionary)
{
    string key = entry.Key;
    int value = entry.Value;
    // Use them...
}

This is equivalent to:

using (var iterator = dictionary.GetEnumerator())
{
    while (iterator.MoveNext())
    {
        var entry = iterator.Current;
        string key = entry.Key;
        int value = entry.Value;
        // Use them...
    }
}

It's very rarely useful to explicitly call GetEnumerator and iterate yourself. It's appropriate in a handful of cases, such as when you want to treat the first value differently, but if you're going to treat all entries the same way, use foreach .

(Note that it really is equivalent to using var here, but not equivalent to declaring an IEnumerator<KeyValuePair<string, int>> - it will actually use the nested Dictionary.Enumerator struct. That's a detail you usually don't need to worry about.)

Answer 3

The foreach statement iterates automatically through enumerators.

foreach (KeyValuePair<string,int> entry in freq) {
    string word = entry.Key;
    int val = entry.Value;
    .......... and so on

}