Find-or-insert with only one lookup in c# dictionary

Question

I\'m a former C++/STL programmer trying to code a fast marching algorithm using c#/.NET technology...

I\'m searching for an equivalent of STL method \"map::insert\"

Answer 1

You can just assign your value in the following way:

var dict = new Dictionary();
dict[2] = 11;

if value with key 2 does not exist - it will be added and otherwise it will be just overriden.

Dictionary does not have method GetOrAdd, but ConcurrentDictionary from C# 4.0 does:

var dict = new ConcurrentDictionary();
dict[2] = 10;
int a = dict.GetOrAdd(2, 11);// a == 10