CODEWITHSUNDEEP
c++vector
Bennett
Bennett

Reputation: 317

Vector.size() producing an unexpectedly large number

I have this program which fills a vectors with float values, ensuring each vector (bin) has less than a sum of 1.0 when the float values are totaled. I discovered through debugging that the program is halting when it tries to add values of a vector to a float. The reason is because the for loop is running more times than elements that exist in the vector. I inserted a cout to check the value of the size, and am getting a very large number (95 million something)

//Bin packing algorithm
//Takes float values which are <1 and packs them into bins.

#include <iostream>
#include <vector>
#include <list>
#include <cassert>

using namespace std;
typedef unsigned int uint;

bool gt( float a, float b )
{
   return b < a;
}

int main()
{
   list< float > S; 
   while( ! cin.eof() )
   {
      float value;
      if( cin >> value && ! cin.eof() )
      {
      assert( value > 0.0 && value <= 1.0 );
         S.push_back( value );
      }
   }

   uint n = S.size();
   uint operations = 0;

   vector< vector< float > > bins;
   S.sort( gt );

   float currentitem;
   float binsum; 

   uint totalbins = 0; 
   uint currentbin; 

   vector<float> tempbin;
   while(S.size() != 0)
   {
      currentitem = S.front();
      S.pop_front();
      currentbin = 0;
      while(currentitem != 0 && totalbins > currentbin)
      {
         currentbin++;
         bintotal = 0;
         for(uint i=0; i < bins[currentbin].size(); i++) 
         {
            cout << "i=" << i <<" bins[currentbin].size()=" << bins[currentbin].size() <<  endl;
            binsum += bins[currentbin][i]; //THIS IS WHERE THE DEBUGGER POINTS. bins[currentbin].size() is producing the 95 million garbage value.
         }
         if((binsum + currentitem) <= 1)
         {
            currentitem = 0;
            bins[currentbin].push_back(currentitem);
         }
      }
      if(currentitem != 0)
      {
         totalbins++;
         tempbin.push_back(currentitem);
         bins.push_back(tempbin);
         tempbin.clear();
      }
   }

Upvotes: 2

Views: 4205

Answers (1)

Asha
Asha

Reputation: 11232

bins[currentbin] in the for loop access invalid bin as currentbin variable is already incremented. You need to currentbin++ after the for loop.

Upvotes: 3

Related Questions