問題描述

最近工作的同事告訴我在設(shè)置字符串變量時(shí)不要使用string.Empty，而是使用null，因?yàn)樗鼤?huì)污染堆棧?

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?

他說不要做

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

這真的很重要嗎?我知道 string 是一個(gè)對(duì)象，所以它有點(diǎn)道理.

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

我知道這是一個(gè)愚蠢的問題，但您的觀點(diǎn)是什么?

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

推薦答案

null 和 Empty 差別很大，不建議隨意切換.但兩者都沒有任何額外的成本"，因?yàn)?Empty 是一個(gè)單一的固定引用(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).

堆棧上沒有由 ldsfld - 這種擔(dān)憂是......瘋狂.加載 null 可以說是稍微更便宜，但如果您不小心檢查值，可能會(huì)導(dǎo)致空引用異常.

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.

就我個(gè)人而言，我兩者都不使用...如果我想要一個(gè)空字符串，我使用 "" - 簡單明了.實(shí)習(xí)意味著這也沒有每次使用的開銷.

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 級(jí)別，"" 和 Empty 之間的區(qū)別只是 ldstr 與 ldsfld - 但兩者都給出了相同的單個(gè)內(nèi)部字符串引用.此外，在最近的 .NET 版本中，JIT 直接攔截了這些，產(chǎn)生空字符串引用實(shí)際上沒有進(jìn)行靜態(tài)字段查找.基本上，除了可讀性之外，完全沒有理由關(guān)心任何一種方式.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 "".

這篇關(guān)于string.Empty vs null.你使用哪個(gè)?的文章就介紹到這了，希望我們推薦的答案對(duì)大家有所幫助，也希望大家多多支持html5模板網(wǎng)！