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docs/api/containers/string/operator-assign.md

@@ -0,0 +1,47 @@
+# String::operator=
+
+```cpp
+String& operator=(const String& other);
+String& operator=(String&& other) noexcept;
+String& operator=(const char* str);
+```
+
+将新的值赋给 String 对象，替换原有的内容。
+
+**参数：**
+- `other` - 另一个 String 对象（拷贝赋值或移动赋值）
+- `str` - 以 null 结尾的 C 字符串
+
+**返回：** `*this`，支持链式调用
+
+**复杂度：**
+- 拷贝赋值：O(n)，n 为 other 的长度
+- 移动赋值：O(1)
+- 从 `const char*` 赋值：O(n)，n 为 str 的长度
+
+**示例：**
+```cpp
+#include "XCEngine/Containers/String.h"
+#include <iostream>
+
+int main() {
+    XCEngine::Containers::String s1;
+    XCEngine::Containers::String s2("hello");
+
+    s1 = s2;               // 拷贝赋值
+    std::cout << s1.CStr() << std::endl;  // 输出: hello
+
+    s1 = "world";          // 从 const char* 赋值
+    std::cout << s1.CStr() << std::endl;  // 输出: world
+
+    XCEngine::Containers::String s3("moved");
+    s1 = std::move(s3);    // 移动赋值
+    std::cout << s1.CStr() << std::endl;  // 输出: moved
+
+    return 0;
+}
+```
+
+## 相关文档
+
+- [String 总览](string.md) - 返回类总览