45 lines
1.1 KiB
Markdown
45 lines
1.1 KiB
Markdown
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# String::Length / Capacity / Empty
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```cpp
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SizeType Length() const;
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SizeType Capacity() const;
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bool Empty() const;
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```
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获取字符串的长度、容量和判空状态。
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**参数：** 无
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**返回：**
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- `Length()` - 返回字符串的字符数（不包括终止 null 字符）
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- `Capacity()` - 返回已分配的存储容量
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- `Empty()` - 如果字符串为空则返回 `true`
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**复杂度：** 均为 O(1)
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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 <iostream>
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int main() {
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XCEngine::Containers::String s1;
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std::cout << "Empty: " << s1.Empty() << std::endl; // 输出: Empty: 1
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XCEngine::Containers::String s2("Hello");
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std::cout << "Length: " << s2.Length() << std::endl; // 输出: Length: 5
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std::cout << "Capacity: " << s2.Capacity() << std::endl; // 输出: Capacity: 6 或更大
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s2.Reserve(100);
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std::cout << "After Reserve(100), Capacity: " << s2.Capacity() << std::endl; // 输出: 100
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return 0;
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}
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```
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## 相关文档
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- [String 总览](string.md) - 返回类总览
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- [CStr](cstr.md) - 获取 C 字符串
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- [Reserve / Resize](reserve-resize.md) - 内存管理
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