Question

I am trying to read this .csv file and here is an example of the data:

1.33286E+12 0   -20.790001  -4.49   -0.762739   -3.364226   -8.962189

1.33286E+12 0   -21.059999  -4.46   -0.721878   -3.255263   -8.989429

The problem is with the first column row 1 and 2. In the excel file it says the numbers in the cells are displayed as 1.33286E+12 and when you click on the cell it says they are 1332856031313 and 1332856031328 but the program is reading them as 1.33286E+12 but I need the whole number 1332856031313 and 1332856031328.

The code:

inputfile.open(word1.c_str());
while (getline (inputfile, line)) //while line reads good
{
  istringstream linestream(line); //allows manipulation of string
  string str;

while (getline (linestream, item, ',')) //extract character and store in item until ','
    {

  char * cstr, *p; 
  cstr = new char [item.size()+1]; 
  strcpy(cstr, item.c_str()); 
  p = strtok(cstr, " "); 

  while (p!=NULL) //while not at the end loop
    {      // double e = atof(p); // coverts p to double
        value++;
        if( value == 1)
                {     double e = atof(p); // coverts p to double
          if(m ==1)
          cout << time[0]<<"\n";

          ostringstream str1;
           str1 << e;
          str = str1.str();
          string str2;
          str2.append(str.begin(), str.end());
          const char * convert = str2.c_str();
          e = atof(convert);
         time[m] = e*0.001;
          m++;
          //if(m >=192542)
          //cout << time[m-1]<<"\n";

        }

               p = strtok(NULL, " ");
    }
  delete[] cstr; //delete cstr to free up space.
}
count ++;
value = 0;
}
inputfile.close();

Answer 1

If the number 1332856031313 is being serialised as 1.33286E+12, there is no way to get it back in the deserialisation process. Information in the form of those 6 extra significant digits is gone forever. You need to make sure that when the CSV file is generated, it is saved at full precision. I don’t know how you might do this with Excel.

Also, your use of atof and const char* isn’t very C++-esque. Consider using code like

double a, b, c, d;
linestream >> a >> b >> c >> d;

instead.