read data from a file with multiple sections from VC++ in VS2013

Question

I need to read a txt file from VC++ in VS2013.

In the file, there are mutiple sections:

 #section1
 head1,head2,head3
 dcscsa, sdew, safce
 .....
 #section2
 head1,head2,head3, head4,head5
 112,633,788,632,235
 .....

I need to save the lines into different data structure for section1: mapSection1>

  for section12
  mapSection2<string, map<string, int>>

Can I use the code :

 string aLine;
 getline(file, aLine);
 stringstream ss(aLine);
 int cnt = 0;
 if (file.good())
 {
    while (!file.eof())
    {
        string substr;
        getline(file, aLine);
        stringstream ss(aLine);
        while (ss.good())
        {
            // how to save data to different map for different section?
        }

Also, i can load the whole file into a data set and then process each line or process each line when the file was read line by line.

Which one is more efficient ?

thanks

Answer 1

Can I use the code : ...

Not quite.

Use:

int sectionNo = 0;
while (getline(file, aLine))
{
    if (aLine.empty()) continue;
    if (aLine[0] == '#')
    {
        ++sectionNo;
        getline(file, aLine); // read headings... use them if you like
        continue;
    }
    std::stringstream ss(aLine);
    switch (sectionNo)
    {
      case 1:
        if (ss >> a >> b >> c >> std::skipws && ss.eof())
            ... use a, b, c ...
        else
            throw std::runtime_error("invalid data in section 1 " + aLine);
        break;
      case 2:
        ...

}

Also, i can load the whole file into a data set and then process each line or process each line when the file was read line by line.

Which one is more efficient ?

Almost always the latter.