while( in.getline(ch, 256, '\n'))
{
   numbers.push_back(atof(ch));
}

std::string line;
 
while( getline(in, line) )
{
   numbers.push_back(atof(line.c_str));
}

psuedocode:
  vector<vector<float>>inputlines
  vector<float>floatvector
 
  while (infile) {
 
       extract one line into a string
       put the string into a strstream
     while (mystrstream) { 
        mystrstream >> myfloat
        floatvector.pushback
     }
     inputlines.pushback(floatvector)
  }

#include <iostream>
#include <fstream>
#include <strstream>
#include <string>
#include <vector>
using namespace std;
 
void main() {
 
 
  ifstream in("in.dat");
  vector<float>numbers;
  float myfloat;
  string input;
 
 
  while (in) {
    getline(in, input);
    numbers.clear();
    strstream myss;
    myss << input;
 
    while(myss) {
      myss >> myfloat;
      numbers.push_back(myfloat);
    }
 
    for (int a = 0; a < numbers.size(); a++)  // outputs one line
      cout << numbers[a] << ", ";
    cout << endl;
    cout << "sizeof numbers: " << numbers.size() << endl;
  }
}

/* mergesort.cpp | John Daniel Leon | johndleon@gmail.com | 10/01/06
 This program sorts numbers using a merge sort algorithm
 Merge sort: O(nlog(n)) - Divides unsorted list in half and sorts each sublist
 Recieves input from file in.dat - NOTE : End of file does not contain a new line. */
 
#include <iostream>
#include <fstream>
#include <sstream>
#include <string>
#include <vector>
 
using namespace std;
 
void GetInput(vector<float> &numbers, vector< vector<float> > &inputlines);
void mergesort(vector<float> &myvec);
void mergesort(vector<float> & a, vector<float> & tmp, int left, int right);
void merge(vector<float> & vec1, vector<float> & vec2, int leftpos, int rightpos, int rightend);
 
void main()
{
  vector<float>numbers;
  vector< vector<float> >inputlines;
 
  GetInput(numbers, inputlines);      // Uses "in.dat" - no new line at EOF
 
  for (int q = 0; q < inputlines.size(); q++)
    mergesort(inputlines[q]);
 
  for (int x = 0; x < inputlines.size(); x++){  
    for (int a = 0; a < inputlines[x].size(); a++)
     cout << inputlines[x][a]; if(a != inputlines[x].size() - 1) cout << ", ";
    cout << endl;
  }
}
 
 
void GetInput(vector<float> & numbers, vector< vector<float> > & inputlines)
 // This function reads "in.dat" file and stores each float number on a line into a float
 // vector. Then the float vectors are stored in a vector called inputlines.
 // This waay I can gather all the data in one procedure and then close the file
 // and move on with the rest of the program. 
 //  NOTE: End of "in.dat" should not contain a newline.
{
  ifstream in("in.dat");
  if(!in)
    cout << "Error reading file: in.dat" << endl;
  string input;
  float myfloat;
 
  while (getline(in, input)) {
    numbers.clear();
    stringstream myss;  
    myss << input;
    while(myss >> myfloat) {
      numbers.push_back( myfloat );
    }
  inputlines.push_back(numbers);
  }
  in.close();
}
 
 
void mergesort ( vector<float> &unsortedvec )
 // Calls mergesort on the unsorted vector and a temporary
 // vector the same size as unsortedvec.
{
  vector<float> temp(unsortedvec.size());
  mergesort(unsortedvec, temp, 0, unsortedvec.size() - 1);
}
 
 
void mergesort(vector<float> & a, vector<float> & tmp, int left, int right)
 // If the size of the vectors is not 1, then it recurses on itself and 
 // then calls merge.
{
  if (left < right)
  {
    int center = (left + right) / 2;
    mergesort(a, tmp, left, center);
    mergesort(a, tmp, (center + 1), right);
    merge(a, tmp, left, (center + 1), right);
  }
}
 
 
void merge(vector<float> & vec1, vector<float> & vec2, int leftpos, int rightpos, int rightend)
 // This is the merge routine. It compares the elements in each vector and manipulates the elements
 // so that vec1 ends up with the final merged(sorted) values.
{
  int leftend = rightpos - 1;
  int tmppos = leftpos;
  int numelements = (rightend - leftpos + 1);
 
  while(leftpos <= leftend && rightpos <= rightend)
    if (vec1[leftpos] <= vec1[rightpos])
      vec2[tmppos++] = vec1[leftpos++];
    else 
      vec2[tmppos++] = vec1[rightpos++];
 
  while(leftpos <= leftend)          // Copy rest of first half
    vec2[tmppos++] = vec1[leftpos++];
 
  while(rightpos <= rightend)        // Copy rest of right half
    vec2[tmppos++] = vec1[rightpos++];
 
  for(int i = 0; i < numelements; i++, rightend--)   //Copy vec2 back
    vec1[rightend] = vec2[rightend];
}