I found an example showing that a dictionary can be initialised as follows:
Dictionary<string, int> d = new Dictionary<string, int>()
{
{"cat", 2},
{"dog", 1},
{"llama", 0},
{"iguana", -1}
};
I don't understand how the syntax {"cat", 2} is valid for creating a Key-Value Pair. Collection initialisation syntax seems to be of the form new MyObjType(){}, while anonymous objects are of the form {a="a", b="b"}. What is actually happening here?
Alright lets take a look at the code here:
Dictionary<string, int> d = new Dictionary<string, int>()
{
{"cat", 2},
{"dog", 1},
{"llama", 0},
{"iguana", -1}
};
a dictionary holds two things, a key, and a value.
your declaration, Dictionary<string, int>, means the keys are strings, and the values are integers.
now, when your adding an item, for instance {"cat", 2},, the key is cat. this would be equivilent to you doing something like, d.Add("cat", 2);. a dictionary can hold anything, from <string, string> to <customClass, anotherCustomClass>. and to call it up you can use int CAT = d["cat"]; to which the value of int CAT would be 2. an example of this would be:
Dictionary<string, int> dict = new Dictionary<string, int>()
{
{"cat", 1}
};
dict.Add("dog", 2);
Console.WriteLine("Cat="+dict["cat"].ToString()+", Dog="+dict["dog"].ToString());
in in there, your adding cat and dog with different values and calling them up
I'm not really sure what your question is asking, but the answer is that this is the syntax for collection initialization that provides a shortcut to the Add method.
This works too, for example:
new List<DateTime>()
{
{DateTime.Now},
{new DateTime()},
{DateTime.Now}
}
Usually when the question is "why is this valid", the answer is because "it is valid" :)
Note that the syntax you specified in the latter part of the question is not just for anonymous objects, its for any object with public property setters:
new MyPerson("Bob")
{
Address = "185 What St",
DoB = DateTime.Now
}
This is a key value pairing. The Dictionary<string,int> says the key will be a string and the value will be an int. Thus with {"cat", 2} you have a key of "cat" and a value of 2. Why you would have a key of cat and a value of 2, I am not sure, but never the less it is an example of a Dictionary<> with a string key and an int value. More info and examples can be found here:
