IPC linux中数组存储的分段错误

Question

I am trying to store a array in shared from a process and tring to access the same from another process.

Below is the code I am using to store the array

#include <iostream> 
    #include <sys/ipc.h> 
    #include <sys/shm.h> 
    #include <stdio.h> 
    #include <stdlib.h>

    using namespace std; 
    int count;
    int main() 
    {

      while(1)
    {
     int arr[5] = {1,2,3,4,5}; 
     int *str1;

     int key=5678;
     // shmget returns an identifier in shmid 
     int shmid = shmget(key,1024, 0666|IPC_CREAT); 
     printf("\nShared Memory Id = %d\n",shmid);

     // shmat to attach to shared memory 
     str1 = (int*) shmat(shmid,(void*)0,0);
     for(int i=0;i<5;i++)
        {
         *str1=arr[i];
          printf("Data written in memory: %d\n",*str1);
          str1++;
        }
    }
    shmdt((void*)str);
    return 0; 
    }

When I am running the program, it is running upto some extend and giving error as segmentation fault (core dumped) and getting exit from the application.

Please help me to solve this problem.

Thanks and regards, Prabhakar M

Answer 1

str1++ is the culprit. Below code is working.

    #include <iostream> 
    #include <sys/ipc.h> 
    #include <sys/shm.h> 
    #include <stdio.h> 
    #include <stdlib.h>

    using namespace std; 
    int count;
    int main() 
    {
 int arr[5] = {1,2,3,4,5}; 
     int *str1;

     int key=5678;
     // shmget returns an identifier in shmid 
     int shmid = shmget(key,1024, 0666|IPC_CREAT); 
     printf("\nShared Memory Id = %d\n",shmid);

     // shmat to attach to shared memory 
     str1 = (int*) shmat(shmid,(void*)0,0);
     int *copyAdrr;
     copyAdrr = str1 ;
     while(1)
    {

     for(int i=0;i<5;i++)
        {
         *str1=arr[i];
          printf("Data written in memory: %d\n",*str1);
          str1++;
        }
        str1 =copyAdrr;
    }
    shmdt((void*)str);
    return 0; 
    }