read file descriptor function in c

[themarioman]

Hi all,

I have problem with read() function. It doesn't read at all. Always return -1. my code is like below:

void myRead()
{
	int fd,ret;
	char buf[BUFSIZ]; 

	fd = open("sam.txt" , O_WRONLY); 	
	if (fd == -1)
	{
		printf("Error in openning the file!\n");
		exit(0);
	}
	//read the file
	ret = read(fd,buf,BUFSIZ);  
	if (ret == -1)
	{
		printf("Error in reading!\n");
		exit(0);
	}
	close(fd);
}

I am sure file can be open, but once start to read it always return -1.

Please suggest or comment. Thanks a lot.


--Mario.


Code Tags added by Kermi3

[kermi3]

I am posting this because you did not use code tags on this thread. In the furture please use Code Tags. They make your code MUCH easier to read and people will be much more likely to help you if you do. And they'll be happy about helping you


For example:

Without code tags:

for(int i=0;i<5;i++)
{
cout << "No code tags are bad";
}

With Code Tags:

for(int i=0;i<5;i++)
{
     cout << "This code is easy to read";
}

This is of course a basic example...more complicated code is even easier to read with code tags than without.

I've added code tags for you this time. They can be added by putting [code] at the beginning of your code and [/code] at the end. More information on code tags may be found at the link in my signature. Any further questions or ways I can help please feel free to PM me.

Good Luck,
Kermi3

[shaik786]

What's the error message you are getting? Include the following line if you don't know how to get the error message:

perror(" read: ");

[[EMOBA]]

You're opening the file for writing, not reading...change your call to open to

fd = open ("sam.txt", O_RDONLY);

. if you on a *nix system, type man 2 open at the command line, and you will see all of the options for file status and mode for the open system call...

-[E]