feat: update structure

cs2106/lectures/l5/1.c

@@ -0,0 +1,32 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <sys/shm.h>
+
+int main() {
+    int shmid, *shm;
+
+    shmid = shmget(IPC_PRIVATE, 4, IPC_CREAT | 0600);
+
+    if (shmid == -1) {
+        printf("Cannot create shared memory!\n");
+        exit(1);
+    } else {
+        printf("Shared memory ID = %d\n", shmid);
+    }
+    shm = (int*) shmat(shmid, NULL, 0);
+    if (shm == (int*) -1) {
+        printf("Cannot attach shared memory!\n");
+        exit(1);
+    }
+    shm[0] = 0;
+    while(shm[0] == 0) {
+        sleep(3);
+    }
+    for(int i = 0; i < 3; i++) {
+        printf("Read %d from shared memory. \n", shm[i+1]);
+    }
+    shmdt((char*) shm);
+    shmctl(shmid, IPC_RMID, 0);
+}
+