What i want to do with the program is to create 3 child processes from one parent . Each child will have 2 pipes connecting to the parent so it can write to the parent and read from it. With this i want the children to communicate with each other trough the parent for example child 1 decides to send a message to child 3 it will first send to the parent then the parent will send it to child 3. To do that i need to make the read pipe ends non blocking. When no massage has been send it works fine but when i try to send something it still writes that pipe is full. My questions is what i am doing wrong?

The example i am following is from this site https://www.geeksforgeeks.org/non-blocking-io-with-pipes-in-c/ . Note that my code is nowhere near finished . I still have a lot of work but i have been stuck on the non blocking. The write at child A near the end is just a test to see if it will send it.

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/wait.h>
#include <time.h>
#include <fcntl.h>
#include <errno.h>

int main()
{
    int pids[3],id[3];
    int pipes[6][2];
    int i;
    for (i=0;i<6;i++)//Creating the pipes
    {
        if (pipe(pipes[i])==-1)
        {
            printf("Error in pipe %dn",i);
            return 0;
        }
        else
        {
            printf("Pipe created!n");
        }
    }



    for(i=0;i<6;i++)//Here i call fcntl for all the pipes
    {
        if (fcntl(pipes[i][0],F_SETFL,O_NONBLOCK)<0)
        {
            printf("Error in fcntl:%d",i);
        }
    }



    for(i=0;i<3;i++)//Store child process id on array
    {
        pids[i]=fork();

        if(pids[i]==0)
        {
            id[i]=getpid();
             break;
        }
    }



    if (getpid()==id[0])//Close pipes that are no neede in child A it keeps 0 and 1
        {
            for (i=0;i<6;i++)
            {
                if (i>0 && i>1)
                {
                    close(pipes[i][0]);
                    close(pipes[i][1]);
                    printf("Ola kala sto klisimo sto A:%dn",i);
                }
            }
            close(pipes[0][1]);
            close(pipes[1][0]);
            return 0;
        }



    if (getpid()==id[1])//Close pipes that are no neede in child B it keeps 2 and 3
        {
            for (i=0;i<6;i++)
            {
                if ((i>2 && i>3) || (i<2 && i<3))
                {
                    close(pipes[i][0]);
                    close(pipes[i][1]);
                    printf("Ola kala sto klisimo sto B:%dn",i);
                }
            }
            close(pipes[2][1]);
            close(pipes[3][0]);
            return 0;
        }



    if (getpid()==id[2])//Close pipes that are no neede in child C it keeps 4 and 5
        {
             for (i=0;i<6;i++)
            {
                if (i<4 && i<5)
                {
                    close(pipes[i][0]);
                    close(pipes[i][1]);
                    printf("Pipe has close in C:%dn",i);
                }
            }
            close(pipes[4][1]);
            close(pipes[5][0]);
            return 0;
        }



    if (getpid()==id[0])//Child A trys to send a massage
    {
       int l=4;
       write(pipes[0][1], &l,sizeof(int));
    }
    if(getpid()!=0)
    {
        sleep(3);
        int nread,buf;
        nread = read(pipes[0][0], &buf, sizeof(int));
        switch (nread) {
        case -1:

            // case -1 means pipe is empty and errono
            // set EAGAIN
            if (errno == EAGAIN) {
                printf("(pipe empty)n");
                sleep(1);
                break;
            }

            else {
                perror("read");
                exit(4);
            }

        // case 0 means all bytes are read and EOF(end of conv.)
        case 0:
            printf("End of conversationn");

            // read link
            close(pipes[0][0]);

            exit(0);
        default:

            // text read
            // by default return no. of bytes
            // which read call read at that time
            printf("MSG = %dn", buf);
        }
    }


    if(getpid()!=0)//The perent waits for all the children
    {

        for(i=0;i<=3;i++)
        {
            wait(NULL);

        }
        printf("PARENT:%dn",getpid());
    }
}

The example i am following is from this site https://www.geeksforgeeks.org/non-blocking-io-with-pipes-in-c/ .Note that my code is nowhere near finished . I still have a lot of work but i have been stuck on the non blocking. The write at child A near the end is just a test to see if it will send it.