feat: update structure

cs2106/lectures/l5/4.c

@@ -0,0 +1,21 @@
+#include <stdio.h>
+#include <signal.h>
+#include <unistd.h>
+#include <stdlib.h>
+
+void myOwnHandler(int signo) {
+  if (signo == SIGSEGV) {
+    printf("Memory Access blows up!\n");
+    exit(1);
+  }
+}
+
+int main() {
+  int *ip = NULL;
+
+  if (signal(SIGSEGV, myOwnHandler) == SIG_ERR) 
+    printf("Failed to register handler\n");
+
+  *ip = 123;
+  return 0;
+}