merging n vectors

[linuxdude]

I have n sorted streams. I was wondering if there was a general way to merge them without the code growing. Here is what I have for 2 streams

int merge_and_print(saga::job::istream out, saga::job::istream out2){
   int temp=-1, temp2=-1;
   if(!out.eof() && !out.fail()){
      out >> temp;
   }
   if(!out2.eof() && !out2.fail()){
      out2 >> temp2;
   }
   while(1){
      if(temp == -1 && temp2 == -1){ std::cout << std::endl << "Done reading output" << std::endl; return 1;}
      if(temp == -1){
         std::cout << temp2 << " ";
         while(!out2.eof() && !out2.fail()){
            out2 >> temp2;
            std::cout << temp2 << " ";
         }
         std::cout << std::endl << "Done reading output" << std::endl; return 1;
      }
      else if(temp2==-1){
         std::cout << temp << " ";
         temp = -1;
          while(!out.eof() && !out.fail()){
            out >> temp;
            std::cout << temp << " ";
         }
         std::cout << std::endl << "Done Reading output" << std::endl; return 1;
      }
      else if(temp <= temp2){
         std::cout << temp << " ";
         if(!out.eof() && !out.fail()){
            out >> temp;
         }
         else temp = -1;
      }
      else if(temp2 < temp){
         std::cout << temp2 << " ";
         if(!out2.eof() && !out2.fail()){
            out2 >> temp2;
         }
         else temp2=-1;
      }
   }
   return 0;

[Daved]

Why not load the data into actual vectors and merge the data in the vectors with an algorithm from <algorithm>?

BTW, does your current code repeat the last value of the streams an extra time?

[Salem]

Calling two input streams 'out' and 'out2' is just too weird.

A vector of N stream references perhaps?

[linuxdude]

I can't load the values from the stream into a vector and then merge because the streams are from jobs that are running in parallel. So I don't think I can do that, but I'm not sure. I think the best way would be a vector of n streams. Thanks. I'll try that.

[Elysia]

You can do it with some thread security if you want. But they're generally expensive and you have to ask yourself if it's worth it.

[iMalc]

I can't load the values from the stream into a vector and then merge because the streams are from jobs that are running in parallel. So I don't think I can do that, but I'm not sure. I think the best way would be a vector of n streams. Thanks. I'll try that.

For better performance when merging from many streams, store pointers to the streams in heap order inside the vector.