From c60876d0780b2ebcc89cf9ea07910d5baeaf30db Mon Sep 17 00:00:00 2001
From: suyangzuo <50766353+suyangzuo@users.noreply.github.com>
Date: Thu, 8 Feb 2024 14:56:15 +0800
Subject: [PATCH] doc: update docs/cs.md (#514)

---
 docs/cs.md | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/docs/cs.md b/docs/cs.md
index 5914a8b..499f640 100644
--- a/docs/cs.md
+++ b/docs/cs.md
@@ -289,6 +289,17 @@ Console.WriteLine(multiLine); // => Content begin "Hello World!" /\n<>"" end.
 
 ### 字符串操作
 
+#### 字符串判空
+
+```cs
+string name; //空引用
+string gender = ""; //空值
+
+// 使用 string.IsNullOrEmpty(字符串) 方法，返回 bool 型
+Console.WriteLine(string.IsNullOrEmpty(name)); //输出 true
+Console.WriteLine(string.IsNullOrEmpty(gender)); // 输出 true
+```
+
 #### 字符串分割
 
 ```cs