使用var或不使用var [英] Using var or not using var
问题描述
可能重复:
C#'var'与特定类型的性能
大家好,
我最近看到了很多使用 var
的代码.
例如:
Hi all,
I recently saw code that uses var
a lot.
E.g.:
var myString = GetAnyString();
var myInstance = GetClass();
代替
string myString = GetAnyString();
MyClass myInstance = GetClass();
除了可读性强(我认为使用 var
不太可读),使用它是否有优点和/或缺点?性能如何
Besides the readability (I think that using var
is not very readable), are there any advantages and/or drawbacks using it? How about performance
推荐答案
var由具有正确类型的编译器替换,因此,除了可能有很小的编译时间开销(veeeeeeeery很小)之外,不会对运行时性能造成影响.
var is replaced by the compiler with the right type, so there is no runtime performance hit, aside from a very small compile time overhead maybe (veeeeeeeery small).
实际上,从可读性的角度来看,我个人如下:
Actually, from a readability point of vue, I personally do as follows:
-
变量实例化:
object myVar = new object();
可变传播: var myVar = anotherVar.getComplexObject();
此外,当您具有非常复杂的类型实例化时,您可能会想使用它们,例如:
Also, you might be tempted to use them when you have a very complex type instantiation, like:
var myDict = new Dictionary<string, List<Tuple<string, object>>>();
在这里,它确实提高了可读性.
Here, it really improves readability.
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