boost :: filesystem获取相对路径

Question

boost::filesystem库的哪些方法可以帮助我获取相对于另一个路径的路径？

我有一个路径/home/user1/Downloads/Books和路径/home/user1/。现在我想要一条路径Downloads/Books。

Answer 1

从链接摘自以下尼科尔挂票发现：

template < > 
    path& path::append< typename path::iterator >(typename path::iterator begin, typename path::iterator end, const codecvt_type& cvt) 
    { 
     for(; begin != end ; ++begin) 
      *this /= *begin; 
     return *this; 
    } 
    // Return path when appended to a_From will resolve to same as a_To 
    boost::filesystem::path make_relative(boost::filesystem::path a_From, boost::filesystem::path a_To) 
    { 
     a_From = boost::filesystem::absolute(a_From); a_To = boost::filesystem::absolute(a_To); 
     boost::filesystem::path ret; 
     boost::filesystem::path::const_iterator itrFrom(a_From.begin()), itrTo(a_To.begin()); 
     // Find common base 
     for(boost::filesystem::path::const_iterator toEnd(a_To.end()), fromEnd(a_From.end()) ; itrFrom != fromEnd && itrTo != toEnd && *itrFrom == *itrTo; ++itrFrom, ++itrTo); 
     // Navigate backwards in directory to reach previously found base 
     for(boost::filesystem::path::const_iterator fromEnd(a_From.end()); itrFrom != fromEnd; ++itrFrom) 
     { 
      if((*itrFrom) != ".") 
       ret /= ".."; 
     } 
     // Now navigate down the directory branch 
     ret.append(itrTo, a_To.end()); 
     return ret; 
    } 

棒，在一个头文件，它应该做你想做的。

样品电话：

boost::filesystem::path a("foo/bar"), b("foo/test/korv.txt"); 
std::cout << make_relative(a, b).string() << std::endl; 

Answer 2

不幸的是，Boost.Filesystem中不存在这样的函数。 It has been requested，但他们似乎并不在乎。

你基本上必须手动完成。

Boost.Filesystem 1.60增加了the relative function可以用来处理这个。

Answer 3

接受的答案的代码不起作用。它应该是

namespace boost { namespace filesystem { 

template <> path& path::append<path::iterator>(path::iterator begin, path::iterator end, const codecvt_type& cvt) 
{ 
    for(; begin != end ; ++begin) 
     *this /= *begin; 
    return *this; 
} 

// Return path when appended to a_From will resolve to same as a_To 
boost::filesystem::path make_relative(boost::filesystem::path a_From, boost::filesystem::path a_To) 
{ 
    a_From = boost::filesystem::absolute(a_From); a_To = boost::filesystem::absolute(a_To); 
    boost::filesystem::path ret; 
    boost::filesystem::path::const_iterator itrFrom(a_From.begin()), itrTo(a_To.begin()); 
    // Find common base 
    for(boost::filesystem::path::const_iterator toEnd(a_To.end()), fromEnd(a_From.end()) ; itrFrom != fromEnd && itrTo != toEnd && *itrFrom == *itrTo; ++itrFrom, ++itrTo); 
    // Navigate backwards in directory to reach previously found base 
    for(boost::filesystem::path::const_iterator fromEnd(a_From.end()); itrFrom != fromEnd; ++itrFrom) 
    { 
     if((*itrFrom) != ".") 
      ret /= ".."; 
    } 
    // Now navigate down the directory branch 
    ret.append(itrTo, a_To.end()); 
    return ret; 
} 

} } // namespace boost::filesystem 

Answer 4

的代码所提供的答案是相当长的，每行。假设你写namespace fs = boost::filesystem;那么这段代码可以让你最的方式，看起来更容易读给我听：

static fs::path relativeTo(fs::path from, fs::path to) 
{ 
    // Start at the root path and while they are the same then do nothing then when they first 
    // diverge take the entire from path, swap it with '..' segments, and then append the remainder of the to path. 
    fs::path::const_iterator fromIter = from.begin(); 
    fs::path::const_iterator toIter = to.begin(); 

    // Loop through both while they are the same to find nearest common directory 
    while (fromIter != from.end() && toIter != to.end() && (*toIter) == (*fromIter)) 
    { 
     ++toIter; 
     ++fromIter; 
    } 

    // Replace from path segments with '..' (from => nearest common directory) 
    fs::path finalPath; 
    while (fromIter != from.end()) 
    { 
     finalPath /= ".."; 
     ++fromIter; 
    } 

    // Append the remainder of the to path (nearest common directory => to) 
    while (toIter != to.end()) 
    { 
     finalPath /= *toIter; 
     ++toIter; 
    } 

    return finalPath; 
} 

Answer 5

在boost新版本（在1.60开始），就可以使用boost::filesystem::relative。 (See the documentation here.)

#include <boost/filesystem.hpp> 
#include <iostream> 
namespace fs = boost::filesystem; 

int main() 
{ 
    fs::path parentPath("/home/user1/"); 
    fs::path childPath("/home/user1/Downloads/Books"); 
    fs::path relativePath = fs::relative(childPath, parentPath); 
    std::cout << relativePath << std::endl; 
}