determining if a file exists (C++)

thanks

Nice memory leak if the file exists. If the file exists you get a file handle, if you do, you ought to fclose it.

That was the C way. In C++ it''s

  if(ifstream("fileName"))
    cout << "exists!";
 

if you are a windows programmer you can use this:

bool exists(const string& fileName)
{
bool returnValue = false;
DWORD attrib = GetFileAttributes(fileName.c_str());
if (attrib != 0xFFFFFFFF)
{
returnValue = true;
}
return returnValue;
}

iirc the file will not be opened by this code.

quote:

---

Original post by sas
bool exists(const string& fileName)
{
bool returnValue = false;
DWORD attrib = GetFileAttributes(fileName.c_str());
if (attrib != 0xFFFFFFFF)
{
returnValue = true;
}
return returnValue;
}

---

Would you by any chance have a programming teacher that smacks you over the head if you have more than one exit point from a function?

quote:

---

Original post by Arild Fines

quote:

---

Original post by sas
bool exists(const string& fileName)
{
bool returnValue = false;
DWORD attrib = GetFileAttributes(fileName.c_str());
if (attrib != 0xFFFFFFFF)
{
returnValue = true;
}
return returnValue;
}

---

Would you by any chance have a programming teacher that smacks you over the head if you have more than one exit point from a function?

---

You should read more carefully, Mister.
There is only one exit point.

I think the point of that comment was criticising your code. It''s written in such a way that is hard to read, but aims at making only one exit point. Basically, it seems like you tried too hard to make that happen.

And i think a simpler function would read

bool exists(const char * filename)
{
return GetFileAttributes(filename) != 0xFFFFFFFF;
}

Which does the same thing(end result).

The test doesn''t guarantee anything, files might be created or deleted at any time, especially between the test and the code that depends on the test.

wow, how did this turn into a flame war, i got the info i needed and, yes, i stuck a close() in there.

Thanks again

Sounds like Mulligan already has it, but just to make it coherent:

bool FileExists( const char* FileName )
{
    FILE* fp = NULL;

    //will not work if you do not have read permissions

    //to the file, but if you don''t have read, it

    //may as well not exist to begin with.

    fp = fopen( FileName, "rb" );
    if( fp != NULL )
    {
        fclose( fp );
        return true;
    }

    return false;
}