Error in Communication between two process using shared memory
 

Forgive me for not using quote, bold and code format due to technical limitation in my system.

I am learning shared memory.I written two file
In 1stfile I am creating segments and writing a string on segment

In second file I am trying to read that shared memory data and trying to print the string.

Error I am getting is segmentation fault while running 2nd file .
Please guide me in this


/* 1st program:shared.c*/

#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/ipc.h>
#include <sys/shm.h>


#define SHM_SIZE 2048 /* make it a 2K shared memory segment */

int main()
{
key_t key;
int shmid;
char *data;

if ((key = ftok("p.c", 'R')) == -1) {
perror("ftok");
exit(1);
}

if ((shmid = shmget(key, SHM_SIZE, IPC_CREAT )) == -1) {
perror("shmget");
exit(1);
}
printf("shmid = %d\n", shmid);

data = shmat(shmid, 0, 0);
if (data == (char *)(-1)) {
perror("shmat");
exit(1);
}

printf("Enter A String:");
gets(data);
printf("\nString %s\n", data);
printf("Address %u\n",data);
printf("Integer val %u",data);


if (shmdt(data) == -1) {
perror("shmdt");
exit(1);
}






/* 2nd program:pro.c*/
#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<sys/types.h>
#include<sys/ipc.h>
#include<sys/shm.h>

int main()
{
key_t key;
char *data;
int shmid;

key = ftok("p.c",'T');
shmid = shmget(key, 2048, IPC_EXCL);
printf("shmid = %d\n", shmid);
printf("key = %ld\n", key);

data =(char *)shmat(shmid,0,0);
printf("Entered Shared Memory Data: %u",data);
printf("Entered Shared Memory Data: %s",data);


return 0;
}

Forgive me for not reading posts whose poster didn't use [code] and [/code] tags.

Your system doesn't have "[" and "]" keys on your keyboard?

I got solved this error by hard coding the key directly in 1st argument of shmget.
Actually ftok was generating different key in different program.Hence segmentation fault

@Nevem Teve.I will stick to rules here after.

@psionl0. Normally I just highlight the text and select tag using mouse.
Thanks you for helping me out that we can do in keyboard.

As a start:

1. Use these compiler options: -g -W -Wall -Wextra -pedantic -Werror

2. At shmget (first program):
3. At shmget (second program):

4. At ftok (second program):