win32下 如何轉換相對路徑(relative path)

相對路徑
一般的作法 就是比對兩個路徑
把兩個路徑normalize一下(例如大小寫 或是 是否兩個都是絕對路徑等等)
一段一段比 比到相異點
再組出相對路徑
其實在win32下面有一個很方便的API
可以幫忙組出相對路徑 但是 這個API必須要link shlwapi.lib喔


PathRelativePathTo
This function takes a pair of paths and generates a relative path from one to the other. The paths do not have to be fully-qualified, but they must have a common prefix, or the function will fail and return FALSE.
<br />BOOL PathRelativePathTo( LPTSTR pszPath,<br /> LPCTSTR pszFrom,<br /> DWORD dwAttrFrom,<br /> LPCTSTR pszTo,<br /> DWORD dwAttrTo<br />);<br />

Sample codes:
<br />#include <windows.h><br />#include <iostream.h><br />#include "Shlwapi.h"<br /><br />void main(void)<br />{<br /> char szOut[MAX_PATH] = "";<br /> char szFrom[ ] = "c:\\a\\b\\path";<br /> char szTo[ ] = "c:\\a\\x\\y\\file";<br /><br /> cout << "The relative path is relative from: ";<br /> cout << szFrom;<br /> cout << "\n";<br /><br /> cout << "The relative path is relative to: ";<br /> cout << szTo;<br /> cout << "\n";<br /><br /> PathRelativePathTo(szOut,<br /> szFrom,<br /> FILE_ATTRIBUTE_DIRECTORY,<br /> szTo,<br /> FILE_ATTRIBUTE_NORMAL);<br /><br /> cout << "The relative path is: ";<br /> cout << szOut;<br /> cout << "\n";<br />}<br /><br />OUTPUT:<br />==================<br />The relative path is relative from: c:\a\b\path<br />The relative path is relative to: c:\a\x\y\file<br />The relative path is: ..\..\x\y\file<br /><br />