Question

I have two lists. Both containing the same values:

 QStringList filePaths;
 filePaths.append("C:/backup");
 filePaths.append("C:/download/file1");
 filePaths.append("D:");
 filePaths.append("C:/program");
 filePaths.append("C:/download");

 QStringList refinedPaths;

 int size = filePaths.size();

 for(int i = 0; i < size; i++)
 {
   refinedPaths.append(filePaths.at(i));
 }

 for(int i = 0; i < size; i++)
 {
   QString str1 = filePaths.at(i);

   for(int j = 0; j < size; j++)
   {
     QString str2 = filePaths.at(j);

     if(str2 == str1)
     {
       continue;
     }

     if(str2.startsWith(str1))
     {
       refinedPaths.removeAll(str2);
     }
   }
 }

What I’m expecting to happen is:
* Iterate through the strings in list, comparing every item in the list with each other.
* If string1 starts with string2 (string2 is therefore the parent directory of string1)
* remove that string from the ‘refined’ stringlist.

Howver, what is happening is that if(str2.startsWith(str1)) is returning true every time, and refinedPaths.removeAll(str2); doesn’t remove any of the strings in the list.

Any ideas?

Answer 1

Your code works fine, not sure what problem you are referring to. Using your code here’s the output I got

C:/backup
D:
C:/program
C:/download

A few things to improve,

1. instead of copying QStringList element by element you can just use the copy constructor i.e copying from filePaths to refinedPaths QStringList refinedPaths(filePaths);

2. use iterators instead of iterating by size().

   QStringList refinedPaths(filePaths);
   
   for(QStringList::const_iterator itr1 = filePaths.begin(); filePaths.end() != itr1 ; ++itr1)
   {
   
     for(QStringList::const_iterator itr2 = filePaths.begin(); filePaths.end() != itr2 ; ++itr2)
     {
       if(*itr1 == *itr2)
       {
         continue;
       }
   
       if(itr2->startsWith(*itr1))
       {
         refinedPaths.removeAll(*itr2);
       }
     }
   }