[SOLVED] small doubt in filehandling

priya sweet · 09-23-2012, 05:19 AM

hello everyone
please help me with the following code:
#include <iostream>
#include <fstream>
using namespace std;
int main()
{
fstream fin;
fin.open("data", ios:: out);
string str;
cin >> str;
fin << str;
fin.close();
fin.open("data", ios::in);
while(fin) {
fin.get(ch);
cout << ch;
}
return 0;
}

if the input is : priya
the output should be priya
but my code is showing the output as priyaa
please help me to sort out the problem with the above code

konsolebox · 09-23-2012, 05:51 AM

Perhaps you mean this:

Code:

#include <iostream>
#include <fstream>
using namespace std;
int main()
{
    fstream fin;
    fin.open("data", ios:: out);
    string str;
    cin >> str;
    fin << str;
    fin.close();
    fin.open("data", ios::in);
    char ch;
    while (fin.get(ch)) {
        cout << ch;
    }
    fin.close();
    return 0;
}

priya sweet · 09-23-2012, 06:20 AM

ohh thank you so much . Now its working properly. But will you please say me what is the difference. And also have a look at this code

#include <iostream>
#include <fstream>

using namespace std;

int main()
{
fstream fin, fin1;
fin.open("copy", ios :: out );

int n;
string str;
cout << "enter no of lines" << endl;
cin >> n;
int i = 0;

do {
getline( cin, str );
fin << str << endl;
i++;
}

while ( i < n );

fin.close();
return 0;
}
In this code i am entering 5 lines but it is taking only 4 lines as input. can u please help me in this case also.what is my wrong here??

konsolebox · 09-23-2012, 08:05 AM

I'm not sure why that happens but as a workaround, you could flush input with ignore() before reading again:

Code:

#include <iostream>
#include <fstream>

using namespace std;

int main()
{
	fstream fin, fout;

	fout.open("copy", ios::out);

	int n;
	string str;

	cout << "enter no of lines" << endl;

	cin >> n;
	cin.ignore();

	for (int i = n; i > 0; --i)
	{
		getline(cin, str);
		fout << str << endl;
	}

	fout.close();

	fin.open("copy", ios::in);

	while (cout << fin.rdbuf())
		;

	fin.close();

	return 0;
}

priya sweet · 09-23-2012, 08:56 AM

thank you so much. My doubt is cleared.