ifstream object seems to be null

[WhatIf]

I'm trying to open a file and read its content but it seems that the ifstream object is null

 DatabaseReader::DatabaseReader()
{
    std::string completePath = "DB.txt";
    std::ifstream DBFile;
    DBFile.open(completePath);
    if(!DBFile.is_open())
    {
        std::cout<<"Database file couldn't be opened :(\n"<<"Exiting......"<<std::endl;
        sleep(5);
        exit(1);
    }
}

DatabaseReader::~DatabaseReader()
{
    DBFile.close();
}

int DatabaseReader::getNumberofAvailableRecords()
{
    std::string recordCount;
    if(DBFile.good())
    {
        DBFile >> recordCount;
        std::cout<<"Number of Records (if): "<<recordCount<<std::endl;
        std::cout<<"DBFile : "<<(DBFile == 0)<<std::endl;
    }
    else
    {
        recordCount = "-1";
        std::cout<<"Number of Records (else): "<<recordCount<<std::endl;
    }
    std::cout<<"Number of Records : "<<recordCount<<std::endl;

    return std::stoi(recordCount);
}

When I run the program I get the following output:

Number of Records (if):
DBFile : 1
Number of Records :
terminate called after throwing an instance of 'std::invalid_argument'
  what():  stoi

This application has requested the Runtime to terminate it in an unusual way.

Since DBFile.good() was executed, I'd assume the file was opened. But (DBFile == 0) or (DBFile == NULL) prints 1.

Then when I attempt to check what was read from file into recordCount, "Number of Records :" prints out with no value. I'm expecting 2 since it's the first line in the file.

What am I doing wrong?

[jlb]

If your file exists then the file could be open, yet if the file is empty then the read of the recordCount could cause the stream to enter a failed state which will leave recordCount in it's default state (empty). Which is what appears to be happening since nothing is printed after the "(if): ".

Also look at the value of DBFile == 0 printout (1), which means that the stream is in a fail state.

By the way why is recordCount a string instead of some kind of number?

[naraku9333]

The DBFile object used to open the file is local to the constructor, so the file is closed after the constructor is finished.

[WhatIf]

I moved std::ifstream DBFile; outside the constructor, before the constructor, and now it's working. But I'm a bit confused. Isn't all initialization supposed to be done inside of the constructor? Why didn't the original code work?