133 lines
3.1 KiB
Markdown
133 lines
3.1 KiB
Markdown
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# String
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**命名空间**: `XCEngine::Containers`
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**类型**: `class`
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**描述**: 动态字符串类，提供 UTF-8 编码的字符串操作。
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## 概述
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`String` 是一个自定义动态字符串类，提供常见的字符串操作功能，支持拷贝构造、移动构造和多种字符串操作方法。
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## 类型别名
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| 别名 | 类型 | 描述 |
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|------|------|------|
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| `SizeType` | `size_t` | 大小类型 |
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## 常量
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| 常量 | 值 | 描述 |
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|------|-----|------|
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| `static constexpr SizeType npos` | `static_cast<SizeType>(-1)` | 无效位置标识 |
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## 公共方法
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### 构造/析构
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| 方法 | 描述 |
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|------|------|
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| [Constructor](constructor.md) | 构造字符串实例 |
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| [Destructor](destructor.md) | 析构函数 |
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| [operator=](operator-assign.md) | 赋值运算符 |
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### 连接运算符
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| 方法 | 描述 |
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|------|------|
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| [operator+=](operator-plus-assign.md) | 追加字符串/字符 |
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| [operator+](operator-plus.md) | 字符串连接 |
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### 比较运算符
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| 方法 | 描述 |
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|------|------|
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| [operator==](operator-equal.md) | 判断两个字符串是否相等 |
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| [operator!=](operator-equal.md) | 判断两个字符串是否不相等 |
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### 字符串操作
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| 方法 | 描述 |
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|------|------|
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| [Substring](substring.md) | 获取子串 |
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| [Trim](trim.md) | 去除首尾空白 |
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| [ToLower/ToUpper](to-lower-upper.md) | 大小写转换 |
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| [Find](find.md) | 查找子串位置 |
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| [StartsWith](starts-with.md) | 检查前缀 |
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| [EndsWith](ends-with.md) | 检查后缀 |
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### 元素访问
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| 方法 | 描述 |
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|------|------|
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| [CStr](cstr.md) | 获取 C 字符串指针 |
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| [Length/Capacity/Empty](size.md) | 获取尺寸信息 |
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| [operator[]](./operator-subscript.md) | 下标访问 |
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### 容量管理
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| 方法 | 描述 |
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|------|------|
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| [Clear](clear.md) | 清空字符串 |
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| [Reserve/Resize](reserve-resize.md) | 预留/调整容量 |
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## std::hash 特化
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```cpp
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namespace std {
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template<>
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struct hash<XCEngine::Containers::String> {
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size_t operator()(const XCEngine::Containers::String& str) const noexcept;
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};
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}
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```
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提供了 `std::hash<String>` 特化，使 `String` 可以作为 unordered_map 或 unordered_set 的键使用。
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**实现算法：** DJB hash (Daniel J. Bernstein hash)
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**算法细节：**
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- 初始值：5381
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- 对每个字符：`hash = hash * 33 + c`（等价于 `(hash << 5) + hash + c`）
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**示例：**
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```cpp
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#include <XCEngine/Containers/String.h>
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#include <unordered_map>
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int main() {
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std::unordered_map<XCEngine::Containers::String, int> map;
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map["key1"] = 100;
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map["key2"] = 200;
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return 0;
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}
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```
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## 使用示例
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```cpp
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#include <XCEngine/Containers/String.h>
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// 基本用法
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Containers::String str = "Hello";
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str += ", World!";
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// 字符串操作
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Containers::String sub = str.Substring(0, 5); // "Hello"
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bool hasPrefix = str.StartsWith("Hello");
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bool hasSuffix = str.EndsWith("!");
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// 查找
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SizeType pos = str.Find("World"); // 返回 7
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// 转换
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Containers::String upper = str.ToUpper();
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Containers::String lower = str.ToLower();
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```
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## 相关文档
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- [Array](../array/array.md) - 动态数组
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- [HashMap](../hashmap/hashmap.md) - 哈希表
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