#include <stdlib.h>
#include <iostream>
#include <string>
#include <fstream>
//defines
#define SPACE std::cout << std::endl;
//classes and vars
std :: string usrname;
std :: string usrpass;
std :: string usrage;
std :: string usremail;
std :: string filename;
std :: string words;
//function prototypes
void input();
void createfile();
//main thingy
using namespace std;
int main()
{
input();
SPACE
system("pause");
return 0;
}
void input()
{
std::cout << "Enter the User Name you want: ";
std::cin >> usrname;
SPACE
std::cout << "Enter the Password you want: ";
std::cin >> usrpass;
SPACE
std::cout << "Enter your age: ";
std::cin >> usrage;
SPACE
std::cout << "Enter your email adress: ";
std::cin >> usremail;
createfile();
}
void createfile()
{
ifstream fin("usernames.txt");
while (getline(fin, words))
{
if (words == usrname)
{
SPACE
cout << "Try another user name :";
SPACE
cin >> usrname;
fin.seekg(0, ios::beg);
}
words = " ";
}
fin.close();
filename= usrname + ".txt";
ofstream fout("usernames.txt");
fout.seekp(NULL, ios::end);
fout << usrname;
}
ofstream delets the contents of my file
Author
Whenever I run this it delets the contents of usernames.txt and replaces it with usrname. I want it to put usnname at the end of the file and leave the rest of the contents alone. Can anyone help?
The problem lies in this line:
By default, when ofstream opens a file for writing, it uses the 'out' openmode - which throws away the current contents of the file. When you come to do your seekp, it's too late - you're seeking to the end of a file that is already empty. What you want to do instead is change your openmode, probably to 'app' (for 'append'):
ofstream fout("usernames.txt");By default, when ofstream opens a file for writing, it uses the 'out' openmode - which throws away the current contents of the file. When you come to do your seekp, it's too late - you're seeking to the end of a file that is already empty. What you want to do instead is change your openmode, probably to 'app' (for 'append'):
ofstream fout("usernames.txt", ios_base::app);
when you open a file & write to it it overwrites whatever was in it you need to use ios::app to append to what was in it
ifstream fin("usernames.txt",ios::app);//i think it should fix it but i'm a noob so don't try many times if it doesn't work it's me who messed up
same goes for
ofstream fout("usernames.txt",ios::app);
ifstream fin("usernames.txt",ios::app);//i think it should fix it but i'm a noob so don't try many times if it doesn't work it's me who messed up
same goes for
ofstream fout("usernames.txt",ios::app);
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