read() returns invalid file descriptor ???
how can this be explained? what am i doing wrong?Code:FILE *mysql; mysql = fopen("mysql.txt","rw"); char buffer[1000]; if (read(mysql,buffer,sizeof(buffer)) > 0) { printf ("%s\n",buffer); }
read(134520840, 0xbfbea748, 1000) = -1 EBADF (Bad file descriptor)
You need to use fread() instead. To be short, file I/O functions come in groups. read() works best if you used open() to get a file descriptor from it. You used fopen(), which is fine.
read() is not a standard function in the C/C++ library.
It is (IIRC) a windows and unix specific function. It does not accept an argument that is a pointer to a FILE: the argument is typically an integer which is a file descriptor returned by a function named open().
You should try to use something like this:
if you want to read file line by line then I suggest using fgets function!Code:fread (buffer, sizeof buffer, 1, mysql);
Last edited by Micko; 08-04-2006 at 06:49 AM.
Gotta love the "please fix this for me, but I'm not going to tell you which functions we're allowed to use" posts.
It's like teaching people to walk by first breaking their legs - muppet teachers! - Salem
> mysql = fopen("mysql.txt","rw");
Read the manual again, "rw" isn't a valid mode.
Also look up the perror() function which will print a wordy description of why various things fail.
Also as noted, you're using read() where you should be using fread()
(Or fopen() where you should be using open())
Either way, make them match up with one another.
If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
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