Thread: reading a file problem

>Hi I am using ifstream but I am using the fstream.h header file does this make a difference?
No, it shouldn't make a difference as long as you use ifstream, and open with:

Code:

ifstream test;
test.open(file);

If it's creating the file anyway, then my guess is a compiler bug, in which case, go with SlyMaelstrom's idea of using the ios::nocreate flag.

Originally Posted by SlyMaelstrom

fstream.h is depreciated. It could likely be the reason your functionality is different than 7stud's. You should probably use <fstream> instead.

That's a good point SlyMaelstrom, I failed to notice the fstream.h. That could be it. And make sure to add:

Code:

using namespace std;

after the includes. So you would change the fstream.h to:

Code:

#include <fstream>
using namespace std;

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

...and with ifstream, no you shouldn't have to use noreplace. The idea is to read from the file it opens... if it replaces the file... there won't be anything to read will there.

thanks does this mean i should remove the .h from all my header files such as:

#include <iostream.h>
#include <fstream.h>
#include <string.h>
#include <stdlib.h>

Yes, if your compiler has them (you might need to keep the .h for a non-standard header file like conio.h).

[edit] Sly beat me. [/edit]

There is a nice article on standard C++ libraries and how they changed. I don't have the link, though.

Basically, all the C++ dedicated libraries, like <iostream.h> and <iomanip.h> just dropped the .h and became <iostream> and <iomanip> and so on.

The old C libraries like <stdio.h> and <time.h> and <ctype.h> dropped the .h and gained a 'c' to the front becoming <cstdio>, <ctime>, and <cctype>, respectively.

As dwks said, non standard libraries still remain their .h extension.

Originally Posted by 182

Thanks again guys, if I were to keep the ifstream.h and use ios::nocreate could this cause any further problems as well?

No and yes... No because it works for you... and yes because that's a terrible reason to use non standard programming. In reality, you should use <fstream> and that shouldn't require the ios::nocreate. That way if someone else were to use your source code it wouldn't cause problems for them.

No, no, no... you should reread what I said.

#include <cstdlib>

Originally Posted by 182

Hi sorry about that, is there an advantage to using the #include <cstdlib> instead of #include <stdlib.h> or is it just because the #include <cstdlib> is the standard?

As long as your compiler supports the new headers, I would always use them. Even if you see an example program with the old headers, before compiling change them to the new ones. Some C++ library headers are:

Code:

<iostream>
<fstream>
<iomanip>
<string>
<sstream>
<vector>
<iterator>
<algorithm>
<bitset>
<list>
<deque>

The C library headers with a 'c' added to the front are:

Code:

<cstdlib>
<cstdio>
<cmath>
<cstring>
<ctime>
<cctype>

Here's a decent library reference: www.cppreference.com