Question

I am using Eclipse C/C++ IDE on Ubuntu and am trying to define a 2D of char as a shared memory between a parent-child processes and am using this :

void fill(char **p)
{
    printf ("int i=0;\n");
    int i=0;
    printf ("int j=0;\n");
    int j=0;
    for(i=0;i<3;i++)
    {
        for(j=0;j<3;j++)
        {
            p[i][j]=' ';
        }
    }
}


int shmid;
char **shmPtr;
if(shmid = shmget(2000, sizeof(char[3][3]), 0)!=-1)
{
    shmPtr = shmat(shmid, 0, 0); //attach shared memory to pointer
    fill(shmPtr);
}

Is this the right way to define the array or not? While trying to fill this array I get a

segmentation fault

.

Answer 1

Just what I suspected. Two-dimensional arrays ain’t double pointers.

void fill(char p[3][3])
{
    int i, j;
    for (i = 0; i < 3; i++) {
        for (j = 0; j < 3; j++) {
            p[i][j] = ' ';
        }
    }
}

int shmid = shmget(2000, sizeof(char[3][3]), 0);
char (*shmPtr)[3] = shmat(shmid, 0, 0);
fill(shmPtr);