diff --git a/codes/c/chapter_stack_and_queue/array_queue.c b/codes/c/chapter_stack_and_queue/array_queue.c
index 9c7ea3e9b..4a00dfdb6 100644
--- a/codes/c/chapter_stack_and_queue/array_queue.c
+++ b/codes/c/chapter_stack_and_queue/array_queue.c
@@ -66,11 +66,12 @@ void push(ArrayQueue *queue, int num) {
 }
 
 /* 出队 */
-void pop(ArrayQueue *queue) {
+int pop(ArrayQueue *queue) {
     int num = peek(queue);
     // 队首指针向后移动一位，若越过尾部则返回到数组头部
     queue->front = (queue->front + 1) % queue->queCapacity;
     queue->queSize--;
+    return num;
 }
 
 /* Driver Code */
@@ -93,7 +94,7 @@ int main() {
     printf("队首元素 peek = %d\r\n", peekNum);
 
     /* 元素出队 */
-    pop(queue);
+    peekNum = pop(queue);
     printf("出队元素 pop = %d ，出队后 queue = ", peekNum);
     printArray(queue->nums, queue->queSize);
 
diff --git a/codes/c/chapter_stack_and_queue/array_stack.c b/codes/c/chapter_stack_and_queue/array_stack.c
index 3c8655883..807c9bca4 100644
--- a/codes/c/chapter_stack_and_queue/array_stack.c
+++ b/codes/c/chapter_stack_and_queue/array_stack.c
@@ -42,7 +42,7 @@ bool isEmpty(ArrayStack *stack) {
 /* 入栈 */
 void push(ArrayStack *stack, int num) {
     if (stack->size == MAX_SIZE) {
-        printf("stack is full.\n");
+        printf("栈已满\n");
         return;
     }
     stack->data[stack->size] = num;
@@ -52,7 +52,7 @@ void push(ArrayStack *stack, int num) {
 /* 访问栈顶元素 */
 int peek(ArrayStack *stack) {
     if (stack->size == 0) {
-        printf("stack is empty.\n");
+        printf("栈为空\n");
         return INT_MAX;
     }
     return stack->data[stack->size - 1];
@@ -60,10 +60,6 @@ int peek(ArrayStack *stack) {
 
 /* 出栈 */
 int pop(ArrayStack *stack) {
-    if (stack->size == 0) {
-        printf("stack is empty.\n");
-        return INT_MAX;
-    }
     int val = peek(stack);
     stack->size--;
     return val;
diff --git a/codes/c/chapter_stack_and_queue/linkedlist_queue.c b/codes/c/chapter_stack_and_queue/linkedlist_queue.c
index df73857fc..9ffdf3b49 100644
--- a/codes/c/chapter_stack_and_queue/linkedlist_queue.c
+++ b/codes/c/chapter_stack_and_queue/linkedlist_queue.c
@@ -67,12 +67,13 @@ int peek(LinkedListQueue *queue) {
 }
 
 /* 出队 */
-void pop(LinkedListQueue *queue) {
+int pop(LinkedListQueue *queue) {
     int num = peek(queue);
     ListNode *tmp = queue->front;
     queue->front = queue->front->next;
     free(tmp);
     queue->queSize--;
+    return num;
 }
 
 /* 打印队列 */
@@ -108,7 +109,7 @@ int main() {
     printf("队首元素 peek = %d\r\n", peekNum);
 
     /* 元素出队 */
-    pop(queue);
+    peekNum = pop(queue);
     printf("出队元素 pop = %d ，出队后 queue = ", peekNum);
     printLinkedListQueue(queue);
 
diff --git a/codes/c/chapter_stack_and_queue/linkedlist_stack.c b/codes/c/chapter_stack_and_queue/linkedlist_stack.c
index 6319fb2c8..25795b286 100644
--- a/codes/c/chapter_stack_and_queue/linkedlist_stack.c
+++ b/codes/c/chapter_stack_and_queue/linkedlist_stack.c
@@ -32,26 +32,16 @@ void delLinkedListStack(LinkedListStack *s) {
 
 /* 获取栈的长度 */
 int size(LinkedListStack *s) {
-    assert(s);
     return s->size;
 }
 
 /* 判断栈是否为空 */
 bool isEmpty(LinkedListStack *s) {
-    assert(s);
     return size(s) == 0;
 }
 
-/* 访问栈顶元素 */
-int peek(LinkedListStack *s) {
-    assert(s);
-    assert(size(s) != 0);
-    return s->top->val;
-}
-
 /* 入栈 */
 void push(LinkedListStack *s, int num) {
-    assert(s);
     ListNode *node = (ListNode *)malloc(sizeof(ListNode));
     node->next = s->top; // 更新新加节点指针域
     node->val = num;     // 更新新加节点数据域
@@ -59,13 +49,17 @@ void push(LinkedListStack *s, int num) {
     s->size++;           // 更新栈大小
 }
 
-/* 出栈 */
-int pop(LinkedListStack *s) {
+/* 访问栈顶元素 */
+int peek(LinkedListStack *s) {
     if (s->size == 0) {
-        printf("stack is empty.\n");
+        printf("栈为空\n");
         return INT_MAX;
     }
-    assert(s);
+    return s->top->val;
+}
+
+/* 出栈 */
+int pop(LinkedListStack *s) {
     int val = peek(s);
     ListNode *tmp = s->top;
     s->top = s->top->next;
diff --git a/codes/cpp/chapter_stack_and_queue/array_queue.cpp b/codes/cpp/chapter_stack_and_queue/array_queue.cpp
index 27c59463d..f12e64e5f 100644
--- a/codes/cpp/chapter_stack_and_queue/array_queue.cpp
+++ b/codes/cpp/chapter_stack_and_queue/array_queue.cpp
@@ -56,11 +56,12 @@ class ArrayQueue {
     }
 
     /* 出队 */
-    void pop() {
+    int pop() {
         int num = peek();
         // 队首指针向后移动一位，若越过尾部则返回到数组头部
         front = (front + 1) % queCapacity;
         queSize--;
+        return num;
     }
 
     /* 访问队首元素 */
@@ -101,7 +102,7 @@ int main() {
     cout << "队首元素 peek = " << peek << endl;
 
     /* 元素出队 */
-    queue->pop();
+    peek = queue->pop();
     cout << "出队元素 pop = " << peek << "，出队后 queue = ";
     printVector(queue->toVector());
 
diff --git a/codes/cpp/chapter_stack_and_queue/array_stack.cpp b/codes/cpp/chapter_stack_and_queue/array_stack.cpp
index c5e5663c5..c59e076b3 100644
--- a/codes/cpp/chapter_stack_and_queue/array_stack.cpp
+++ b/codes/cpp/chapter_stack_and_queue/array_stack.cpp
@@ -28,9 +28,10 @@ class ArrayStack {
     }
 
     /* 出栈 */
-    void pop() {
-        int oldTop = top();
+    int pop() {
+        int num = top();
         stack.pop_back();
+        return num;
     }
 
     /* 访问栈顶元素 */
@@ -65,7 +66,7 @@ int main() {
     cout << "栈顶元素 top = " << top << endl;
 
     /* 元素出栈 */
-    stack->pop();
+    top = stack->pop();
     cout << "出栈元素 pop = " << top << "，出栈后 stack = ";
     printVector(stack->toVector());
 
diff --git a/codes/cpp/chapter_stack_and_queue/linkedlist_queue.cpp b/codes/cpp/chapter_stack_and_queue/linkedlist_queue.cpp
index a1769359a..0d2bd58e0 100644
--- a/codes/cpp/chapter_stack_and_queue/linkedlist_queue.cpp
+++ b/codes/cpp/chapter_stack_and_queue/linkedlist_queue.cpp
@@ -52,7 +52,7 @@ class LinkedListQueue {
     }
 
     /* 出队 */
-    void pop() {
+    int pop() {
         int num = peek();
         // 删除头节点
         ListNode *tmp = front;
@@ -60,6 +60,7 @@ class LinkedListQueue {
         // 释放内存
         delete tmp;
         queSize--;
+        return num;
     }
 
     /* 访问队首元素 */
@@ -100,7 +101,7 @@ int main() {
     cout << "队首元素 peek = " << peek << endl;
 
     /* 元素出队 */
-    queue->pop();
+    peek = queue->pop();
     cout << "出队元素 pop = " << peek << "，出队后 queue = ";
     printVector(queue->toVector());
 
diff --git a/codes/cpp/chapter_stack_and_queue/linkedlist_stack.cpp b/codes/cpp/chapter_stack_and_queue/linkedlist_stack.cpp
index c51a46b78..dbf1f6724 100644
--- a/codes/cpp/chapter_stack_and_queue/linkedlist_stack.cpp
+++ b/codes/cpp/chapter_stack_and_queue/linkedlist_stack.cpp
@@ -42,13 +42,14 @@ class LinkedListStack {
     }
 
     /* 出栈 */
-    void pop() {
+    int pop() {
         int num = top();
         ListNode *tmp = stackTop;
         stackTop = stackTop->next;
         // 释放内存
         delete tmp;
         stkSize--;
+        return num;
     }
 
     /* 访问栈顶元素 */
@@ -89,7 +90,7 @@ int main() {
     cout << "栈顶元素 top = " << top << endl;
 
     /* 元素出栈 */
-    stack->pop();
+    top = stack->pop();
     cout << "出栈元素 pop = " << top << "，出栈后 stack = ";
     printVector(stack->toVector());
 
diff --git a/docs/chapter_preface/about_the_book.md b/docs/chapter_preface/about_the_book.md
index 5d1e08f61..f79e13b45 100644
--- a/docs/chapter_preface/about_the_book.md
+++ b/docs/chapter_preface/about_the_book.md
@@ -43,4 +43,4 @@
 
 本书倡导手脑并用的学习方式，在这一点上深受[《动手学深度学习》](https://github.com/d2l-ai/d2l-zh)的启发。在此向各位读者强烈推荐这本优秀的著作。
 
-衷心感谢我的父母，正是你们一直以来的支持与鼓励，让我有机会做这件富有趣味的事。
+**衷心感谢我的父母，正是你们一直以来的支持与鼓励，让我有机会做这件富有趣味的事**。