C# 5.0 Programmer's Reference

Literal Type Characters ❘ 69
NOTE The syntax List creates a List object that manipulates
strings. List is a generic class and in this example string is its generic parameter.
Chapter 14, “Collection Classes,” says more about generic collection classes.
The items inside the braces must include all the values needed by the collection’s Add method. For
example, the Dictionary class’s Add method takes two parameters giving a key/value pair that should
be added. That means each entry in the initializer should include a key and value.
The following code initializes a Dictionary (dictionary with keys that are
strings and associated values that are strings). The parameters to the class’s Add method are an
item’s key and value so, for example, the value 940-283-1298 has the key Alice Artz. Later you could
look up Alice’s phone number by searching the Dictionary for the item with the key "Alice Artz".
Dictionary directory = new Dictionary()
{
{"Alice Artz", "940-283-1298"},
{"Bill Bland", "940-237-3827"},
{"Carla Careful", "940-237-1983"}
};
Initializing Without Add
Some collection classes such as Stack and Queue don’t have an Add method, so this
kind of initializer doesn’t work for them. Fortunately, they have constructors that
take a parameter that can be an enumerable type such as a list or array. That means
you can pass the constructor an array of values to be added to the Stack or Queue
as in the following code.
Stack stack = new Stack(new int[] { 1, 2, 3, 4 });
Queue queue = new Queue(new int[] { 4, 3, 2, 1 });
Literal Type Characters
If your code includes a literal value such as a number, C# uses a set of rules to interpret the value.
For example, the value 2000000000 fits in the int data type, so when a C# program sees that
value, it assumes it is an int.
In contrast, the value 3000000000 does not fit in the int data type, so the program assumes this
value is a uint, which is big enough to hold the value. A uint cannot hold a negative value, however,
so if the program contains the value –3000000000, C# makes it a long.
When a value looks like an integer, the program tries to interpret it as the smallest integer data type
at least as large as int (so it doesn’t consider byte, sbyte, short, or ushort).
When a value includes a decimal point, the program assumes it is a double.
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