本文介绍了哪个性能更好?和安道尔一样的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!

问题描述

在编写If语句时,我总是在需要时使用,如:

When writing an If statement, I've always used And when needed like:

If 1=1 And 2=2 Then

我唯一使用过的时间 AndAlso 如果第二个条件会出错,如果第一个条件不是这样的话:

The only time I ever used AndAlso is if the second condition will error if the first isnt true like:

If Not IsDbNull(Value) AndAlso Value=2 Then

然而,最近我听说过 AndAlso 的性能优于,因为只有当第一个条件为真时才会读取第二个条件。

However, recently I've heard that AndAlso is better for performance than And as the second condition is only read when the first is true.

在这种情况下,我应该只使用 AndAlso

In this case, should I always just use AndAlso?

推荐答案

是的, AndAlso 可以快于,因为它不会如果先前的条件证明是错误的,则评估后续条件。

Yes, AndAlso can be faster than And, because it doesn't evaluate subsequent conditions if an earlier condition proves false.

是对早期版本的Visual Basic的回归。 br>
大多数(我毫不犹豫地说)所有现代语言都使用布尔运算符那些不严格需要评估的短路情况。

And is a throwback to earlier versions of Visual Basic.
Most (I hesitate to say all) modern languages use boolean operators that short-circuit conditions that don't strictly need to be evaluated.

例如。 && C风格语言的和运算符都表现为 AndAlso

e.g. && the and operator for C style languages all perform as AndAlso.

如果你有很多使用的代码,请注意全球如果第二个条件涉及具有副作用的函数调用,则搜索和替换可以更改现有行为。

Be careful if you've lots of code that use And and Or, a global search and replace can change existing behaviour, if the second condition involves a function call that has side effects.

我更喜欢使用 AndAlso OrElse 除非您特别要求&提供的功能。

I would prefer using AndAlso and OrElse unless you specifically require the functionality provided by And & Or

这篇关于哪个性能更好?和安道尔一样的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持!

09-15 13:46