C PROGRAM THAT ILLUSTRATES THE FOLLOWING: a. Creating a message queue. b. Writing to a message queue. c. Reading from a message queue.

C PROGRAM THAT ILLUSTRATES THE FOLLOWING:
   a. Creating a message queue.
   b. Writing to a message queue.
   c. Reading from a message queue.
#include<stdio.h>
#include<stdlib.h>

#include<unistd.h>

#include<string.h>

#include<sys/ipc.h>

#include<sys/shm.h>

#include<sys/types.h>

#include <fcntl.h>
 #define MAX 255

        struct mesg

        {

              long type;

              char mtext[MAX];

        }*mesg;

        char buff[MAX];

 main()

 {

        int mid,fd,n,count=0;
        if((mid=msgget(1006,IPC_CREAT | 0666))<0)

        {
                printf("\n Can’t create Message Q");

                exit(1);

        }
        printf("\n Queue id:%d", mid);

        mesg=(struct mesg *)malloc(sizeof(struct mesg));

        mesg->type=6;
        fd=open("fact",O_RDONLY);

        while(read(fd,buff,25)>0)

        {
                strcpy(mesg->mtext,buff);

                if(msgsnd(mid,mesg,strlen(mesg->mtext),0)== -1)

                     printf("\n Message Write Error");

        }

       if((mid=msgget(1006,0))<0)

        {

                printf("\n Can’t create Message Q");
                exit(1);

        }
        while((n=msgrcv(mid,&mesg,MAX,6,IPC_NOWAIT))>0)

                write(1,mesg->mtext,n);
                count++;

        if((n==-1)&(count==0))
                printf("\n No Message Queue on Queue:%d",mid);

 }