c pipe read string is empty - c

Question

I just want to create 2 new forks(child processes) and they will put their name sequentally. SO first they need to some string in pipe to check something. Let's see the code:
char myname[] = "ALOAA";
int main ()
{
int fds[2];
pid_t pid;
pipe(fds);
pid = fork();
if(pid == 0)
{
strcpy(myname, "first");
}
else
{
pid = fork();
if(pid == 0)
{
strcpy(myname, "second");
}
}
if(strcmp(myname, "ALOAA") != 0)
{
char readbuffer[1025];
int i;
for (i = 0; i < 2 ; i++)
{
//printf("%s\n", myname);
close(fds[0]);
write(fds[1], myname, strlen(myname));
while(1)
{
close(fds[1]);
int n = read(fds[0], readbuffer, 1024);
readbuffer[n] = 0;
printf("%s-alihan\n", readbuffer);
if(readbuffer != myname)
break;
sleep(1);
}
//printf("%s\n", myname);
}
}
return 0;
}
So the first process will write her name to pipe. And after that, will check if any new string in pipe. It will be same for second too. However I got empty string from read() function. So it prints like that
-alihan
-alihan
I couldn't get the problem.

Answer 1

However I got empty string from read() function [...] I couldn't get the problem.
#MikeCAT nailed this issue with his observation in comments that each child closes fds[0] before it ever attempts to read from it. No other file is assigned the same FD between, so the read fails. You do not test for the failure.
Not testing for the read failure is a significant problem, because your program does not merely fail to recognize it -- it exhibits undefined behavior as a result. This arises for (at least) two reasons:
read() will have indicated failure by returning -1, and your program will respond by attempting an out-of-bounds write (to readbuffer[-1]).
if we ignore the UB resulting from (1), we still have the program thereafter reading from completely uninitialized array readbuffer (because neither the read() call nor the assignment will have set the value of any element of that array).
Overall, you need to learn the discipline of checking the return values of your library function calls for error conditions, at least everywhere that it matters whether an error occurred (which is for most calls). For example, your usage of pipe(), fork(), and write() exhibits this problem, too. Under some circumstances you want to check the return value of printf()-family functions, and you usually want to check the return value of input functions -- not just read(), but scanf(), fgets(), etc..
Tertiarily, your usage of read() and write() is incorrect. You make the common mistake of assuming that (on success) write() will reliably write all the bytes specified, and that read() will read all bytes that have been written, up to the specified buffer size. Although that ordinarily works in practice for exchanging short messages over a pipe, it is not guaranteed. In general, write() may perform only a partial write and read() may perform only a partial read, for unspecified, unpredictable reasons.
To write successfully one generally must be prepared to repeat write() calls in a loop, using the return value to determine where (or whether) to start the next write. To read complete messages successfully one generally must be prepared similarly to repeat read() calls in a loop until the requisite number of bytes have been read into the buffer, or until some other termination condition is satisfied, such as the end of the file being reached. I presume it will not be lost on you that many forms of this require advance knowledge of the number of bytes to read.