Improve delete_value function logic

Refactor delete_value function to handle head, last, and middle node deletions more clearly.

DoublyLL.c

@@ -24,6 +24,7 @@ void insert(int value) {
     newNode->data = value;
     newNode->next = NULL;
 
+    /* Case 1: Empty list */
     if (head == NULL) {
         newNode->prev = NULL;
         head = newNode;
@@ -31,6 +32,7 @@ void insert(int value) {
         return;
     }
 
+    /* Case 2: List not empty → go to last node */
     temp = head;
     while (temp->next != NULL) {
         temp = temp->next;
@@ -42,31 +44,43 @@ void insert(int value) {
     printf("Inserted %d\n", value);
 }
 
-/* Delete node by value */
+/* Delete node by value (HEAD / MIDDLE / LAST handled) */
 void delete_value(int value) {
     NODE *temp = head;
 
+    /* Case 0: Empty list */
     if (head == NULL) {
         printf("List is empty\n");
         return;
     }
 
+    /* Search for the node */
     while (temp != NULL && temp->data != value) {
         temp = temp->next;
     }
 
+    /* Value not found */
     if (temp == NULL) {
         printf("Element not found\n");
         return;
     }
 
-    if (temp == head) {
-        head = temp->next;
-        if (head != NULL)
-            head->prev = NULL;
-    } else {
+    /* Case 1: Deleting HEAD node */
+    if (temp->prev == NULL) {
+        head = temp->next;      // move head forward
+        if (head != NULL) {
+            head->prev = NULL;  // new head prev must be NULL
+        }
+    }
+
+    /* Case 2: Deleting LAST node */
+    else if (temp->next == NULL) {
+        temp->prev->next = NULL;
+    }
+
+    /* Case 3: Deleting MIDDLE node */
+    else {
         temp->prev->next = temp->next;
-        if (temp->next != NULL)
         temp->next->prev = temp->prev;
     }
 
@@ -105,6 +119,7 @@ int main() {
         scanf("%d", &choice);
 
         switch (choice) {
+
         case 1:
             printf("Enter value: ");
             scanf("%d", &value);