var keyword "Go" in C #

"Turn" http://blog.csdn.net/courageously/article/details/5695626

The VAR keyword is a new feature in C # 3.0, called inferred type. A local variable can be given the inferred "type" var instead of an explicit type. The VAR keyword instructs the compiler to infer the type of the variable based on the expression on the right side of the initialization statement. The inferred type can be a built-in type, an anonymous type, a user-defined type, a type defined in a. NET Framework class Library, or any expression. The above information is a bit abstract and difficult to understand. Example: Originally we define variables, that is to say: Data type variable name = value; such as: int a = 1; String B = "2"; That is, "You must explicitly" specify what data type your variable is in order to assign a value to it. This is important, so remember to compare. Now in C # 3.0, there is a change, that is, you can not define the variable as above. such as: var a = 1; What kind of a is that? It's not the same as the original. The secret here is that the IDE or compiler will "infer that" A is an integer type based on the value you give to a: 1. similarly: var B = "2"; Because the value given to B is a string such as "2", so B is the string type ...

Another example:

var is a 3.5 new definition of the type of the variable is actually the weakening type of the definition of Var can be substituted for any type of compiler will be based on the context to determine what type you want to use in the case of Var I think you can not be sure what type you will use var similar OB Ject but efficiency has the following four characteristics when using VAR to define variables than object highs: 1. Must be initialized at the time of definition. It must be var s = "ABCD" form, not the following form: Var s; s = "ABCD"; 2. Once initialization is complete, it is not possible to assign a value that differs from the initialization value type. 3. The var requirement is a local variable. 4. Using var to define variables is different from object, which is exactly the same as defining variables in terms of efficiency and using strongly typed methods.

var keyword "Go" in C #