Question

我想知道我是否可以使用std :: replace来用单引号替换字符串流中的双引号。

我有：

unarchiver(_:cannotDecodeObjectOfClassName:originalClasses:)

但是当然ostreambuf_iterator没有默认构造函数，所以这不会编译。

是否有另一种方法可以像这样替换字符串流中出现的char？

Answer 1

假设字符串的生成者在生成字符串时仅使用ostream的{{1}}接口，那么它是可能的（一旦你破译文档，实际上很容易）构建一个自定义的ostream，它既可以过滤也可以附加到您可以完全访问的字符串。

示例：

stringstream

预期产出：

#include <boost/iostreams/device/back_inserter.hpp>
#include <boost/iostreams/filtering_stream.hpp>
#include <iostream>
#include <string>

namespace io = boost::iostreams;

// a custom filter
struct replace_chars
{
    typedef char                   char_type;
    typedef io::output_filter_tag  category;


    replace_chars(char_type from, char_type to) : from(from), to(to) {}

    template<typename Sink>
    bool put(Sink& snk, char_type c)
    {
        if (c == from) c = to;
        return io::put(snk, c);
    }

    char_type from, to;
};

// some code that writes to an ostream    
void produce_strings(std::ostream& os)
{
    os << "The quick brown fox called \"Kevin\" jumps over the lazy dog called \"Bob\"" << std::endl;
    os << "leave 'these' as they are" << std::endl;
    os << "\"this\" will need to be flushed as there is no endl";
}

// test
int main()
{
    // a free buffer to which I have access
    std::string buffer;

    // build my custom ostream    
    io::filtering_ostream stream;
    stream.push(replace_chars('"', '\''));   // stage 1 - filter
    stream.push(io::back_inserter(buffer));  // terminal stage - append to string

    // pass the ostream interface of my filtering, string-producing stream    
    produce_strings(stream);
    // flush in case the callee didn't terminal with std::endl
    stream.flush();

    std::cout <<buffer <<std::endl;
}

Answer 2

std::stringstream类提供了一个操作流的接口，而不是其内容。要操纵流的内容，您必须获取字符串，对其进行操作，然后将字符串放入流中，如下所示：

#include <iostream>
#include <sstream>
#include <algorithm>
#include <string>

int main(void)
{
    std::stringstream ss;
    ss << "\"this is a string in a stream\"";
    std::cout << "Before: " << ss.str() << std::endl;
    std::string s = ss.str();
    std::replace(s.begin(), s.end(), '"', '\'');
    ss.str(s);
    std::cout << "After: " << ss.str() << std::endl;
    return 0;
}

你得到：

之前：＆＃34;这是一个流中的字符串＆＃34;
之后：＆＃39;这是一个流中的字符串＆＃39;

替换std :: stringstream inline中的chars

2 个答案: