diff --git a/图书管理系统.c b/图书管理系统.c
index 01c428f..514604e 100644
--- a/图书管理系统.c
+++ b/图书管理系统.c
@@ -174,7 +174,39 @@ Book* AddBook(Book* book1)
     return;
 }
 //C5
-
+Book* DealoldBook(Book* book1)
+{
+    Book* book = book1;
+    Book* prev = book1;
+    printf("输入要处理旧书的编号:");
+    int id;
+    scanf("%d", &id);
+    getchar();
+    while (book != NULL)
+    {
+        if (id == book->iNum)
+        {
+            if (book1 == book)
+            {
+                book = book->next;
+                free(prev);
+                return book;
+            }
+            prev->next = book->next;
+            free(book);                     // free():释放资源
+            printf("已将旧书处理掉!\n");
+            printf("按任意键返回\n");
+            getchar();
+            return book1;
+        }
+        prev = book;
+        book = book->next;
+    }
+    printf("没有找到该图书\n");
+    printf("按任意键返回\n");
+    getchar();
+    return book1;
+}
 //C6
 
 //C7