string.Empty vs null.你使用哪个?

问题描述

最近工作的同事告诉我在设置字符串变量时不要使用string.Empty，而是使用null，因为它会污染堆栈?

Recently a colleague at work told me not to use string.Empty when setting a string variable but use null as it pollutes the stack?

他说不要做

string myString=string.Empty; 但是做 string mystring=null;

这真的很重要吗?我知道 string 是一个对象，所以它有点道理.

Does it really matter? I know string is an object so it sort of makes sense.

我知道这是一个愚蠢的问题，但您的观点是什么?

I know is a silly question but what is your view?

推荐答案

null 和 Empty 差别很大，不建议随意切换.但两者都没有任何额外的成本"，因为 Empty 是一个单一的固定引用(您可以多次使用它).

null and Empty are very different, and I don't suggest arbitrarily switching between them. But neither has any extra "cost", since Empty is a single fixed reference (you can use it any number of times).

堆栈上没有由 ldsfld - 这种担忧是......疯狂.加载 null 可以说是稍微更便宜，但如果您不小心检查值，可能会导致空引用异常.

There is no "pollution" on the stack caused by a ldsfld - that concern is.... crazy. Loading a null is arguably marginally cheaper, but could cause null-reference exceptions if you aren't careful about checking the value.

就我个人而言，我两者都不使用...如果我想要一个空字符串，我使用 "" - 简单明了.实习意味着这也没有每次使用的开销.

Personally, I use neither... If I want an empty string I use "" - simple and obvious. Interning means this also has no per-usage overhead.

在 IL 级别，"" 和 Empty 之间的区别只是 ldstr 与 ldsfld - 但两者都给出了相同的单个内部字符串引用.此外，在最近的 .NET 版本中，JIT 直接拦截了这些，产生空字符串引用实际上没有进行静态字段查找.基本上，除了可读性之外，完全没有理由关心任何一种方式.我只用".

At the IL level, the difference here between "" and Empty is just ldstr vs ldsfld - but both give the same single interned string reference. Furthermore, in more recent .NET versions the JIT has direct interception of these, yielding the empty string reference without actually doing a static field lookup. Basically, there is exactly no reason to care either way, except readability. I just use "".