将值比较为null.为什么会这样呢? [英] Compare a value to null. Why is this true?

问题描述

为什么是

isTRUE(NULL != 2)
[1] FALSE

我将如何获得TRUE?

And how would I receive TRUE?

在我的真实情况下，我有变量，并且如果值不同，我想处理一些东西.但是，当一个值为NULL时，我不会将它们识别为不同！

In my real case I have variables and I want to process something, if the values differ. However, when one value is NULL I don't recognize them as different!

推荐答案

正如@Roland指出的那样，我们不能直接在NULL对象上执行任何逻辑运算.为了比较它们，我们可能需要执行is.null的附加检查，然后执行逻辑比较.

As @Roland pointed out, we can't perform any logical operations directly on NULL object. To compare them we might need to perform an additional check of is.null and then perform the logical comparison.

我们可以使用identical来比较处理整数和NULL的值.

We can use identical instead to compare values which handles integers as well as NULL.

identical(4, 2) 
#FALSE

identical(NULL, 2) 
#FALSE

identical(2, 2) 
#TRUE

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