How to implement msgq message queue in CPP C C++

//Program to implement msgq

/*CPP Program for msg queue in Linux

pipes work with related process parent-child only.

Fifo can make unrelated process to communicate but

fifo created does not persists for use in future.

Shared memory is similar to fifo but over comes this and can be used later also.

Program to implement IPC Message Queues IPC mechanism.

msgqSendkirk.c adds the message on the message queue.

msgqRecvSpock.c reads and removes the message from the message

queue.To use this program first compile and run msgqSendkirk.c

to add a message to the message queue. To see the

Message Queue in other terminal run msgqRecvSpock.c

ipcs -q shows the msg ques.

ipcrm -q 131073 removes the msgq created say 131071 */

#include <stdio.h>
#include <stdlib.h>

#include <errno.h>

#include <string.h>

#include <sys/types.h>

#include <sys/ipc.h>

#include <sys/msg.h>

//1. declaring the msg structure

struct my_msgbuf

{

long mtype;

char mtext[200];

};

int main(void)

{

struct my_msgbuf buf;

int msqid;

key_t key;

//2. creating key with ftok

key = ftok("msgqSendkirk.c", 'B');

///local/kumarsah/comp/linuxdemo/msgqSendkirk.c

//3. creating msgq with msgget

msqid = msgget(key, 0644 | IPC_CREAT);

printf("Enter lines of text, ^D to quit:\n");

buf.mtype = 1;

//4. type and send the message

while(fgets(buf.mtext, sizeof buf.mtext, stdin) != NULL)

{

int len = strlen(buf.mtext);

msgsnd(msqid, &buf, len+1, 0);

}

//5. removing msgq with msgctl with IPC_RMID

msgctl(msqid, IPC_RMID, NULL) ;

return 0;

}

// msgqRecvSpock.c

#include <stdio.h>

#include <stdlib.h>

#include <errno.h>

#include <sys/types.h>

#include <sys/ipc.h>

#include <sys/msg.h>

struct my_msgbuf {

long mtype;

char mtext[200];

};

int main(void)

{

struct my_msgbuf buf;

int msqid;

key_t key;

if ((key = ftok("msgqSendkirk.c", 'B')) == -1) {/* same key as msgqSendkirk.c */

perror("ftok");

exit(1);

}

if ((msqid = msgget(key, 0644)) == -1) { /* connect to the queue */

perror("msgget");

exit(1);

}

printf("spock: ready to receive messages:\n");

for(;;) { /* Spock never quits! */

if (msgrcv(msqid, &buf, sizeof(buf.mtext), 0, 0) == -1) {

perror("msgrcv");

exit(1);

}

printf("spock: \"%s\"\n", buf.mtext);

}

return 0;

}

/*terminal 1:

$ gcc msgqSendkirk.c

$ ./a.out

Enter lines of text, ^D to quit:

dwqdadd

aaaaaaaaa

ddddd

ddd

dd

terminal2:

gcc msgqRecvSpock.c

$ ./a.out

spock: ready to receive messages:.

spock: "dwqdadd"

sldjslds

spock: "aaaaaaaaa"

spock: "ddddd"

ddd

d

*/

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