类型转换的性能 [英] Performance of TypeCasting

问题描述

有

((TypeA) obj).method1();
((TypeA) obj).method2();
((TypeA) obj).method3();

和

var A = (TypeA) obj;
A.method1();
A.method2();
A.method3();

使用很多时候？

when used alot of times?

我经常看到类似

if (((TextBox)sender).Text.Contains('.') || ((TextBox)sender).Text.Contains(','))

和不知道这是一种浪费的表现。

and wonder if this is a waste of performance.

推荐答案

这可能是可衡量的，如果它正在做几十亿次用很少的其他工作。我不知道CLR是否会有效地缓存，中投工作的事实，所以它并不需要再次做到这一点 - 如果它没有这样做，现在，它可能会在以后的版本这样做。它可能这样做，在64位的JIT但不是32位版本，或反之亦然 - 你的想法。我怀疑这会使得在正常code一显著的差异，但。

It may be measurable if it's being done billions of times with very little other work. I don't know whether the CLR will effectively cache the fact that the cast worked, so it doesn't need to do it again - if it doesn't do so now, it might do so in a later release. It might do so in the 64 bit JIT but not the 32 bit version, or vice versa - you get the idea. I doubt that it would make a significant difference in normal code though.

我个人喜欢的的可读性第二种形式的多，虽然，这是更重要的是迄今为止。

Personally I like the readability of the second form more though, and that's more important by far.

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