Anyone know of a function to...

...return the difference between two absolute paths?

For my project, I need to pass two actual paths to a function so I can set the relative path of the second actual path passed.

For example, if I pass c:\folder1\ and c:\folder1\folder2\folder3, the function will return folder2\folder3 - as this is the difference between the two. This makes it easy to link to my second path relatively from my first path, if you see what I mean.

Thanks for any help,

Jim

I am not aware of such a function...so I would guess you would come up with your own one... :cool:

Okay Andreas, thanks.

If anyone has already written anything like this, it would be a real help if you could show me the function.

Thanks
Jim

It's actually quite simple with std::string.

Code:

---

#include <string>
using namespace std;

string PathDiff(const string &first, const string &second)
{
        // Search if the second string contain the first string
        if(second.find(first) == 0)
        {
                // Removing the occurence of the first string in second string.
                return second.substr( first.length() );
        }

        return second;
}

---

Cheers Kheun, that's helpful.

What I need is a little more complicated than that though, because the two absolute paths will not always be on the same branch. For example, I might pass c:\folder\folder1, and c:\folder\folder2, in which case the function will need to return ..\folder2 ...etc.

It needs to be able to give the difference in any paths passed.

I am starting to write this myself now and will probably use what you have written as the template for this. I'm a little new to this though so it's not too easy for me.

Thanks
Jim

Okay, it's a little long-winded, but here is the function I have written to deal with this - if it's of use to anyone else. As I say, I'm a bit new so it's probably not written particularly well, and there may be something I've overlooked, but it seems to work :)

Cheers,
Jim

Code:

---

CString AbsolutePathDiff(CString path1, CString path2)
{
//ignore 0 as this will be the drive
        int count=1;
        int file1check=0, file2check=0;

        CString path1buf;       
        CString path2buf;       
        CString newpath;       
        CString dirsback;       

        newpath.Empty();
        dirsback.Empty();

//1. loop through both paths grabbing folders one-by-one       
        while(TRUE)
        {
                file1check=AfxExtractSubString(path1buf, path1, count, '\\');
                file2check=AfxExtractSubString(path2buf, path2, count, '\\');

//no path left to grab so break out
                if(file1check==0 && file2check==0)
                {
                        break;
                }               

                if(file1check==0)
                {                       
                        newpath.Insert(newpath.GetLength()+1, path2buf);
                        newpath.Insert(newpath.GetLength()+1, "\\");
                }
                else if(file2check==0)
                {                       
                        dirsback.Insert(0, "..\\");
                }
                else if(path1buf.CompareNoCase(path2buf)!=0)
                {                       
                        dirsback.Insert(0, "..\\");
                        newpath.Insert(newpath.GetLength()+1, path2buf);
                        newpath.Insert(newpath.GetLength()+1, "\\");
                }               

                count++;
        }

        newpath.Insert(0, dirsback);

        return newpath;
}

---

Just some advice: I would rewrite your function to use std::string in place of CString. There's no need to lock yourself down to requiring MFC when it's not necessary.

CString is no longer MFC specific, and why would you want to lock yourself down to a slow std:string class? :) *joking*

Quote:

---

Originally Posted by carribus

CString is no longer MFC specific

---

:confused: Was that part of the joke?

Can't rewrite it 'cause I don't gots time! ;)

Quote:

---

Originally Posted by Jim1981

...return the difference between two absolute paths?

For my project, I need to pass two actual paths to a function so I can set the relative path of the second actual path passed.

For example, if I pass c:\folder1\ and c:\folder1\folder2\folder3, the function will return folder2\folder3 - as this is the difference between the two. This makes it easy to link to my second path relatively from my first path, if you see what I mean.

---

If you are programming for Windows paltforms, try the PathRelativePathTo() which is part of the SHLWAPI.dll (IE 5.0+). These are the shell APIs for IE, they are documented in MSDN, or see the shlwapi.h file in your include directory (VC++ installations).