How To Modify An Element in the Dictionary Class?

[complete]

How To Modify An Element in the Dictionary Class?
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C# has this cool Dictionary class that you can use like a Hash Table. Is there a way of changing the value of an indexed element without resorting to removing it like this?

               int value = runningcount[city];
               runningcount.Remove(city);
               runningcount.Add(city, ++value);

 

[LuminaryJanitor]

Looks like this should do it.

 

[dogbert_2001]

runningcount[city]++;

 

[Kaos]

runningcount[city]++;

I don't do C# but this is pretty much what I was thinking, or if it's beyond a simple iteration

runningcount[city] += whatever

I believe i've done this in other languages.

 

[mikeblas]

"runningcount[city]" evaluates to a reference to the object you looked up with the key "city". With that reference, you can do anything you'd like to the object.

 

[Whatsisname]

why don't you just write a test program to find out for yourself? What happens if you do:

FooDictionary[5] = new Bar();

when there is no element with index 5, and see what happens? Maybe it will throw an exception, maybe it won't.

You can also read the documentation and example program provided, it might tell you all the answers: http://msdn.microsoft.com/en-us/library/xfhwa508.aspx

 

[mpoon2489]

runningcount[city]++;

This works for int, but if you want a general manipulation of a dictionary element:

dict[key] = function(dict[key])

where

function()

is whatever you want

 

[Zangmonkey]

As has been noted here, you can simply write to the dictionary by key.

myDictionary[myKey] = myValue

This will *add or replace* without giving you feedback on what has happened.

Consider whether you need to know when something has been inserted versus overwritten.

 

[mikeblas]

is whatever you want

As long as it returns a reference to a payload object, yeah.