return and call dynamic string array

Question

I created a class:

    Data::Data(char szFileName[MAX_PATH]) {

    string sIn;
    int i = 1;

    ifstream infile;
    infile.open(szFileName);
    infile.seekg(0,ios::beg);

    std::vector<std::string> fileRows;
    while ( getline(infile,sIn ) )
    {
      fileRows.push_back(sIn);
    }
}

after that i created this:

std::vector<std::string> Data::fileContent(){
        return fileRows;
}

After that I would like to call this fileContent() somewhere, something like this:

Data name(szFileName);
MessageBox(hwnd, name.fileContent().at(0).c_str() , "About", MB_OK);

But this doesnt work... How to call this?

sorry Adatkezeles = Data Data name(szFileName); MessageBox(hwnd, name.fileContent().at(0).c_str() , "About", MB_OK); and i got this error: terminate called after throwing an instance of 'std::out_of_range' what(): vector::_M_range_check — szuniverse
– szuniverse, Commented Mar 18, 2013 at 11:52
@David: Please use the edit link to update your question with this information. Also, you probably want Data::fileContent() to (a) be const-qualified and (b) to return std::vector<std::string> by reference. — johnsyweb
– johnsyweb, Commented Mar 18, 2013 at 11:55

AndersK · Accepted Answer · 2013-03-18 11:55:01Z

2

std::vector<std::string> fileRows;
while ( getline(infile,sIn ) )
{
   fileRows.push_back(sIn);
}

does not work because you declare fileRows in the constructor, once the constructor ends fileRows is destroyed.

What you need to do is to move the fileRows declaration outside of the constructor and make it a class member:

class Data
{
...

   std::vector<std::string> fileRows;
};

then it will be shared by all functions in the class.

answered Mar 18, 2013 at 11:55

AndersK

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billz · Accepted Answer · 2013-03-18 11:56:12Z

1

You could do like this:

#include <string>
#include <vector>

class Data
{
public:
  Data(const std::string& FileName)  // use std::string instead of char array
  {
     // load data to fileRows
  }

  std::string fileContent(int index) const  // and you may don't want to return a copy of fiileRows
  {
      return fileRows.at(index);
  }

private:
    std::vector<std::string> fileRows;
};

answered Mar 18, 2013 at 11:56

billz

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