??合并为空字符串? [英] ?? Coalesce for empty string?

问题描述

我发现自己做的越来越多的事情是检查字符串是否为空(如""或null)和条件运算符.

Something I find myself doing more and more is checking a string for empty (as in "" or null) and a conditional operator.

当前示例:

s.SiteNumber.IsNullOrEmpty() ? "No Number" : s.SiteNumber;

这只是扩展方法，等效于:

This is just an extension method, it's equivalent to:

string.IsNullOrEmpty(s.SiteNumber) ? "No Number" : s.SiteNumber;

由于它为空且不为null，因此??不会解决问题. ??的string.IsNullOrEmpty()版本将是理想的解决方案.我在想必须有一种更清洁的方法(我希望！)，但是我一直茫然地找不到它.

Since it's empty and not null, ?? won't do the trick. A string.IsNullOrEmpty() version of ?? would be the perfect solution. I'm thinking there has to be a cleaner way of doing this (I hope!), but I've been at a loss to find it.

有人知道有更好的方法吗，即使仅在.Net 4.0中也是如此?

Does anyone know of a better way to do this, even if it's only in .Net 4.0?

推荐答案

没有内置的方法可以做到这一点.您可以使扩展方法返回字符串或null，但这将允许合并运算符起作用.但是，这很奇怪，我个人更喜欢您当前的方法.

There isn't a built-in way to do this. You could make your extension method return a string or null, however, which would allow the coalescing operator to work. This would be odd, however, and I personally prefer your current approach.

由于您已经在使用扩展方法，为什么不制作一个返回值或默认值的扩展方法呢?

Since you're already using an extension method, why not just make one that returns the value or a default:

string result = s.SiteNumber.ConvertNullOrEmptyTo("No Number");

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