Problem opening blank files with ifstream.

I'm having problems opening blank files with ifstream. It seems to be saving a blank line over my first string variable. For example I created a completely blank text file in notepad and saved it as SAVEGAME.DAT. I then try to open it with the following code.

Code:

---

#include <cstdlib>
#include <iostream>
#include <string>
#include <fstream>

using namespace std;
   
int main()
{
    int a = 0;
    string tempString[3];
    tempString[0] = "empty";
    tempString[1] = "empty";
    tempString[2] = "empty";
       
    ifstream myStream("SAVEGAME.DAT");
    while(!myStream.eof())
    {
    getline(myStream, tempString[a]);
    a++;
    }
    cout << tempString[0] << endl;
    cout << tempString[1] << endl;
    cout << tempString[2] << endl;
    system("PAUSE");
    return 0;
}

---

This gives the the output of:

Code:

---

1. [first line is blank]
2. empty
3. empty
4. Press any key to continue.

---

So somehow its saving over my first string variable even though the SAVEGAME.DAT file is completely blank

It works fine however if SAVEGAME.DAT has a line of text in it. When I open SAVEGAME.DAT and insert and save some text. For example if I save the word "sometext" in SAVEGAME.DAT. I get the following:

Code:

---

1. sometext
2. empty
3. empty
4. Press any key to continue.

---

This is working fine^ It only doesn't work right if the file is blank.

Thank you!

I think the problem is with controlling input loop with eof (see FAQ why you shouldn't do that). See, before the loop eof is not true. The first input will be performed anyway.

Another option is that there is a blank line in the file (are you sure the size of the file is 0 bytes?).

You were right, thanks anon!

Here is updated code that works great for my save game function in my game just in case anyone has similar problems to this in the future and stumbles upon this on the google or something

Code:

---


#include <string>
#include <iostream>
#include <cstdlib>
#include <fstream>

using namespace std;

int main()
{
 int tmpInt =0;
 string tmpString;
 string stringArray[4];
 stringArray[0] = "empty";
 stringArray[1] = "empty";
 stringArray[2] = "empty";
 stringArray[3] = "empty";
 
 ifstream myStream("SAVEGAME.DAT");
 while(!(myStream.peek() == EOF))
 {
getline(myStream, tmpString);
stringArray[tmpInt] = tmpString;     
tmpInt++;   
 }
 
 for (tmpInt = 0; tmpInt < 4; tmpInt++)
 {
  cout << stringArray[tmpInt] << endl;     
 }
 
 myStream.clear();
 myStream.close();
 system("PAUSE");
 return 0; 
}

---

Peeking is not the standard way to do it either. Input functions themselves report back whether input was successful (or more precisely, whether the input stream is in a good state), so they can be used to control looping directly:

Code:

---

while (geline(myStream, string))...

---

Your code, as it is, doesn't try to avoid going out of bounds either. What if there happens to be more than 4 lines in the file?

Code:

---

std::vector<std::string> stringVector;
std::string lineFromFile;
std::ifstream inFile("somefile.txt");

while (getline(inFile,lineFromFile))
{
  stringVector.push_back(lineFromFile);
}

inFile.close();

---

You could possibly blow size_t but that would be a very large file.