获取std :: wstring的子字符串 [英] getting a sub string of a std::wstring

问题描述

如何获得包含一些非ASCII字符的 std :: wstring 的子字符串？

How can I get a substring of a std::wstring which includes some non-ASCII characters?

以下代码不会输出任何内容：

（文本是一个阿拉伯字包含4个字符，每个字符有两个字节，加上Hello字样）

The following code does not output anything:
(The text is an Arabic word contains 4 characters where each character has two bytes, plus the word "Hello")

#include <iostream>
#include <string>

using namespace std;

int main()
{
    wstring s = L"سلام hello";
    wcout << s.substr(0,3) << endl;
    wcout << s.substr(4,5) << endl;

    return 0;
}

推荐答案

> Live on Coliru

This should work: live on Coliru

#include <iostream>
#include <string>
#include <boost/regex/pending/unicode_iterator.hpp>

using namespace std;

template <typename C>
std::string to_utf8(C const& in)
{
    std::string result;
    auto out = std::back_inserter(result);
    auto utf8out = boost::utf8_output_iterator<decltype(out)>(out);

    std::copy(begin(in), end(in), utf8out);
    return result;
}

int main()
{
    wstring s = L"سلام hello";

    auto first  = s.substr(0,3);
    auto second = s.substr(4,5);

    cout << to_utf8(first)  << endl;
    cout << to_utf8(second) << endl;
}

列印

سلا
 hell

strong>虽然，我认为你的 substring 调用做奇怪的假设。让我在一分钟内建议修正：

Frankly though, I think your substring calls are making weird assumptions. Let me suggest a fix for that in a minute:

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