Reading In Deletes My .txt File

[Rusticus]

I'm working on a program that will read in from a text file and store in a person struct, but what seems to happen is that whenever I try to read in even just a simple name or line, it just removes all text from the .txt file.

Here is a look at my code.

#include <iostream>
#include <string>
#include <vector>
#include <fstream>

using namespace std;

struct Person{
	string firstName;
	string lastName;
	char sex;
	int age;

};

void fillVector(){
	string fileName;
	
	ofstream dataOut;
	ifstream dataIn;
	fstream filestream;
	bool run = true;
	string tempLast;
	string tempFirst;
	
	while(run==true){
		cout << "Please enter the name of your file: ";
		cin >> fileName;
		filestream.open (fileName);
  
		if (filestream.is_open()){
			cout << "File successfully opened.\n";
			filestream.close();
			run=false;
		}
		else{
			cout << "Error opening file, please check if the file name you entered was correct.\n";
		}
	}
	
	dataIn.open(fileName);
	dataOut.open(fileName);
		
		while(!dataIn.eof()){
			getline(dataIn, tempLast);
			cout << tempLast;
		}
		
		if(dataIn.eof()){
			cout << "End of file reached.\n";
		}
}

The current text that is in my .txt file is "Anderson". My goal would be to run the program and after I type in the file name, have "Anderson" be output to my console. After running the program, the text file is cleared of any text I put in. Right now all that is being output is.

Please enter the name of your file: namefile.txt
File successfully opened.
End of file reached.
Press any key to continue...

[Chervil]

The description of this project implies the file will be opened for input. This is what is done.

	ifstream dataIn;
	dataIn.open(fileName);

However, for reasons not explained in the description, there is also this code:

	ofstream dataOut;
	dataOut.open(fileName);

Here the same filename is opened for output. Using the default settings as here, will cause the length of the file to be set to zero.

I don't understand the intention of the ofstream. Right now I'd suggest removing it as it is the direct cause of the problem.

[Rusticus]

You were exactly right, I deleted those lines and it now works as expected. Thank you!