A question about ifstream

With a background in DOS, I always understood that newlines in text files required TWO characters rather than one like on UNIX. So if I'm reading one character at a time using get(), how can I check for a newline?

Secondly, how can I check if a file exists? Someone suggested I use access() but I couldn't find that documented anywhere.

Thanks a lot!

hi,

you could check for newline with the '\n'

then you could check if the file opens successfuly with the
ifstream::fail() command,

ie,
// to check if open successfully
ifstream fin("data.dat");
if(fin.fail())
return false;
// to check for new line
while(fin.get(ch) != '\n')

:)

Yup, in C++ newline is always one character.

hmm., that's weird, i just tried using ifstream::fail() to check if the file opens successfully, now it won't work, you have similar problems?

EDIT: alright, it's really weird. I got my c++ book and just to make sure if i'm really makign the right way, well, i am, but it's not working :(

So am I to understand that the file stream swallow the CR/LF characters and replaced it with one character?

Code:

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'\n'

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is one character (hence the use of ' rather than "... if that makes any sense :))

the slash is used in C++ so that the compiler now that it's not just a letter.

Quote:

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Originally posted by JMB
So am I to understand that the file stream swallow the CR/LF characters and replaced it with one character?

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Yes, in text mode, these 2 characters are converted into 1. However, open you file in binary mode, and you'll get both. (... this is talking about reading a file)

Hammer,

Thank you for the clarification. How can I use ifstream in binary mode so that I get the file exactly byte-for-byte? I thought get() would solve that problem but apparantly not...

-JMB

Code:

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

/* */
int main(void)
{
    ifstream f;
    int c;
       
    f.open("junk1.c", ios::in | ios::binary);
   
    if (!f)
    {
        cout <<"open error" <<endl;
        return 1;
    }
   
    while ((c = f.get() ) != EOF)
    {
        switch (c)
        {
            case '\n': cout <<"LF found\n"; break;
            case '\r': cout <<"CR found\n"; break;
            default: break;
        }
    }
    return(0);
}

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Quote:

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but I couldn't find that documented anywhere.

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msdn.microsoft.com has just about everything, just type in a function name and if it exists you will find a complete documentation of the function, i.e its parameters, description of what it does and even examples. I use it often. It also has functions listed there not related to windows, i.e opengl functions

Thanks a lot!