vbNullString、String.Empty 和“"之间有什么区别? [英] What is the difference between vbNullString, String.Empty and ""?

问题描述

所有这些

• txtUsername.Text <>vbNullString
• txtUsername.Text <>String.Empty
• txtUsername.Text <>""

似乎返回相同的结果.那么，vbNullString、String.Empty 和 "" 有什么区别?

seem to return the same result. So, what's the difference between vbNullString, String.Empty and ""?

推荐答案

vbNullString 是一个常量，更可能是在 VB6 中，String.Empty 和 "" 是同样，有人说有性能差异，但事实并非如此，使用什么是您的选择.

vbNullString is a constant, more likely out of VB6, String.Empty and "" are the same, some say that there is a performance difference, but that is not true, it is your choice what you use.

要检查字符串是否为空，您可以使用If String.IsNullOrEmpty(String).优点是它还会检查 null，因为 string 是一个类，因此它是一个引用类型.

To check whether a string is empty you can use If String.IsNullOrEmpty(String). The advantage is that it will also check for null, because string is a class and because of this a reference type.

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