Platform::String 真的那么没用吗? [英] Is Platform::String really so useless?

问题描述

我正在尝试在Windows Store"(又名 Metro 风格)应用程序中用 C++/CX 编写几行代码，我很惊讶地看到 Platform::String 缺少许多基本字符串操作，例如 "替换" 或 索引".

I am trying to write a few lines of code in C++/CX in a "Windows Store" (aka Metro Style) application, and I am surprised to see that Platform::String is missing many basic string operations like "replace" or "index of".

我想我可以使用内部数据，将其传递给 std:string 实例并应用我需要的操作，但我想知道我是否遗漏了一些仅限平台::*"执行这些操作的方式.

I suppose I could use the internal data, pass it to a std:string instance and apply the operations I need, but I would like to know if I am missing some "Platform::* only" way of doing these operations.

请注意这个问题是关于 C++/CX，而不是 C#.

推荐答案

Windows 运行时字符串类型，HSTRING 是不可变的并且是引用计数的.

The Windows Runtime string type, HSTRING is immutable and is reference counted.

C++/CX 中的 Platform::String 类型只是 HSTRING 类型及其支持的少数操作的包装器(请参阅以Windows 运行时 C++ 函数 列表中的 Windows.

The Platform::String type in C++/CX is simply a wrapper around the HSTRING type and the handful of operations that it supports (see the functions that start with Windows in the Windows Runtime C++ Functions list).

没有改变字符串的操作，因为字符串类型是不可变的(因此没有Replace).有一些非变异操作(肯定少于 C++ 的 std::wstring).

There are no operations that mutate the string because the string type is immutable (hence why there is no Replace). There are a few non-mutating operations (certainly fewer than C++'s std::wstring).

Platform::String 确实提供了 Begin() 和 End() 成员函数(以及非成员 begin() 和 end() 重载)将随机访问迭代器返回到字符串中(它们返回指针，wchar_t const*，并且指针是有效的随机访问迭代器).您可以将这些迭代器与任何采用随机访问迭代器的 C++ 标准库算法一起使用，并且不会尝试改变底层序列.例如，考虑使用 std::find 来查找字符第一次出现的索引.

Platform::String does provide Begin() and End() member functions (and non-member begin() and end() overloads) that return random access iterators into the string (they return pointers, wchar_t const*, and pointers are valid random access iterators). You can use these iterators with any of the C++ Standard Library algorithms that take random access iterators and do not attempt to mutate the underlying sequence. For example, consider using std::find to find the index of the first occurrence of a character.

如果您需要对字符串进行变异，请使用 std::wstring 或 std::vector.理想情况下，考虑在您的程序中尽可能多地使用 C++ std::wstring，并且只在需要与其他 Windows 互操作的地方使用 C++/CX Platform::String运行时组件(即，跨越 ABI 边界).

If you need to mutate a string, use std::wstring or std::vector<wchar_t>. Ideally, consider using the C++ std::wstring as much as possible in your program and only use the C++/CX Platform::String where you need to interoperate with other Windows Runtime components (i.e., across the ABI boundary).

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