File Handling

[aleeza]

I wanna make a program, but could not make,Plz provide me its code in c++.
The program is:

Write a program that read a text file, one line at a time, and prints the line as it was read and then prints the line with its text reversed. Print a blank line after each reversed line.

[Incubbus]

Why could´t You make it?... Got ill with lazynoobitis?...

[aleeza]

Provide me c++ coding of this, Hurry

[Galik]

Do you want to at least make an attempt?

Then we can help you if you make a mistake.

[aleeza]

how to read line by line?

[aleeza]

I have tried as follows. but not reading line by line plz correct it


#include<iostream.h>
#include<conio.h>
#include<fstream.h>
#include<stdio.h>
#include<string.h>
void main()
{
clrscr();
char arr[100];

ofstream file("c:\\array.txt",ios::app);
ifstream file1("c:\\array.txt");
for(int i=0;i<5;i++)
{
cout<<"Enter value in text";
cin>>arr[i];
file<<arr[i]<<endl;
}
//ofstream file("c:\\array.txt",ios::app);
//ifstream file1("c:\\array.txt");
//file<<<<'\n';
//cout<<"The string is as follows:"<<endl;
//cout<<str;
for(i=0;i<5;i++)
{
file << "The is line "<<i;
}
file.close();

//cout<<"The list of string is as follows:"<<endl;
//while(!file1.eof())
//{
//while(getline(file1,line));
//cout<<"["<<line<<"]"<<endl;
file1.close();
getch();
}

[Galik]

Thank you.

If you want to read in lines from a file it is best to use std::getline with std::string

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

std::ifstream file_in("c:\\in_file_name.txt");

std::string line;

std::getline(file_in, line);

Then you can output the string like this:

file_out << line << std::endl;

I hope that helps.

[Albatross]

main() must return an int, the in in the other for loop is not defined (you need an int before it), and aside from that it should compile just fine.

EDIT: Also, please don't use conio.h, though, if you can avoid it.

-Albatross

[aleeza]

I have a confusion about std, plz tell me what is std?

[Galik]

The standard libraries that come with C++ are in the std namespace.

That means you need to put std:: in front of the classes and types that come from the standard libraries.

So if you want to use a standard file stream you would include <fstream> and use the std::fstream class:

#include <fstream>

std::ifstream input("my_input_file.txt");

The std:: just tells the compiler that you want the one from the standard library.

Here: http://www.cplusplus.com/doc/tutorial/namespaces/

[aleeza]

I have compile the following program, but not working .There are 14 errors in it. Plz Correct it.
Even i have used namespace std,but not working, plz correct.




#include<iostream.h>
#include<fstream.h>
#include<stdio.h>
#include<string.h>
using namespace std;

void main()
{
clrscr();
char arr[100];
std::ofstream file("c:\\std.txt",ios::app);
std::ifstream file1("c:\\std.txt");
std::string line;
for(int i=0;i<5;i++)
{
cout<<"Enter value in text file";
cin>>arr[i];
file<<arr[i]<<endl;
file.close();
}

[aleeza]

The above program is not complete. the following program is complete. plz correct



#include<iostream.h>
#include<fstream.h>
#include<stdio.h>
#include<string.h>
using namespace std;

void main()
{
clrscr();
char arr[100];
std::ofstream file("c:\\std.txt",ios::app);
std::ifstream file1("c:\\std.txt");
std::string line;
for(int i=0;i<5;i++)
{
cout<<"Enter value in text file";
cin>>arr[i];
file<<arr[i]<<endl;
file.close();
}

std::getline(file1,line);
file<<line<<std::endl;
file1.close();

getch();
}

[Galik]

Okay I have posted some corrections.

You should not use the old headers in c++.

Don't include <iostream.h>, use <iostream> instead.

Also with the c headers us the c++ versions of those as well.

For instance not <stdio.h> but <cstdio> (remove the .h from the end and put 'c' at the beginning.

// Don't use the .h form headers in c++

//#include<iostream.h>
//#include<fstream.h>
//#include<stdio.h>
//#include<string.h>

// Use these instead

#include <iostream>
#include <fstream>
#include <cstdio>
#include <cstring>

using namespace std;

//void main() // ERROR!
int main() // main function MUST be int
{
	//clrscr();
	char arr[100];
	std::ofstream file("c:\\std.txt", ios::app);
	std::ifstream file1("c:\\std.txt");
	std::string line;
	for (int i = 0; i < 5; i++)
	{
		cout << "Enter value in text file";
		cin >> arr[i];
		file << arr[i] << endl;
		file.close();
	}

	std::getline(file1, line);
	file << line << std::endl;
	file1.close();

	//getch();
	return 0; // should return a value from main!
}

That version compiles for me :)

[aleeza]

As you said that i should not use .h but then compiler does not open files.
there are errors like:
Unable to open cstdio
unable to pen cstring
and so on
none of any file is opening.
plz tell its solution

[Galik]

Then it sounds like your compiler installation is not working properly.

What compiler/platform are you using?

[aleeza]

Turbo C

[Galik]

Turbo C? Not C++?

That could be your problem...?

[Galik]

Maybe get a different compiler?

This environment has the GCC C++ compiler tools

http://sourceware.org/cygwin/

Or there may be other for windows. Its not my platform though.