From 7c8cf9a2ca6820d5d84cb9c2b1f4a9303ed144e3 Mon Sep 17 00:00:00 2001
From: heimoshuiyu <heimoshuiyu@gmail.com>
Date: Tue, 16 Mar 2021 08:28:56 +0800
Subject: [PATCH] week 3 comment and destory function

---
 week3/stack.c | 29 +++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)

diff --git a/week3/stack.c b/week3/stack.c
index 325614f..96bba9f 100644
--- a/week3/stack.c
+++ b/week3/stack.c
@@ -1,3 +1,10 @@
+/*
+ * Author: Walter
+ * Student ID: 1930006025
+ * Week_3
+ * Stack
+ */
+
 #include <stdio.h>
 #include <stdbool.h>
 #include <stdlib.h>
@@ -6,6 +13,7 @@
 
 #include "stack.h"
 
+/* test function */
 int main() {
 	Stack stack;
 	double val;
@@ -31,13 +39,16 @@ int main() {
 }
 
 bool CreateStack(Stack *stack, int size) {
+	/* check */
 	assert(size > 0);
 
+	/* memory allocate */
 	stack->data = (double *)malloc(sizeof(double) * size);
 	if (stack->data == NULL) {
 		return false;
 	}
 
+	/* init attribute */
 	stack->top = -1;
 	stack->size = size;
 
@@ -45,33 +56,46 @@ bool CreateStack(Stack *stack, int size) {
 }
 
 bool IsEmpty(Stack *stack) {
+	/* if empty, stack->top = -1 */
 	return stack->top < 0;
 }
 
 bool IsFull(Stack *stack) {
+	/* if full, stack->top = stack->size */
 	return stack->top >= stack->size;
 }
 
 bool Top(Stack *stack, double *x) {
+	/* check empty */
 	if (IsEmpty(stack)) {
 		return false;
 	}
+
+	/* get top */
 	*x = stack->data[stack->top];
+
 	return true;
 }
 
 bool Push(Stack *stack, double x) {
+	/* check */
 	if (IsFull(stack)) {
 		return false;
 	}
+
+	/* push */
 	stack->data[++stack->top] = x;
+
 	return true;
 }
 
 bool Pop(Stack *stack, double *x) {
+	/* check */
 	if (IsEmpty(stack)) {
 		return false;
 	}
+
+	/* get x, and top - 1 */
 	*x = stack->data[stack->top--];
 	return true;
 }
@@ -79,8 +103,10 @@ bool Pop(Stack *stack, double *x) {
 void DisplayStack(Stack *stack) {
 	double *top_p = stack->data + stack->top;
 
+	/* print the top pointer hint */
 	printf("top --> ");
 	
+	/* loop for stack data */
 	for (; top_p >= stack->data; top_p--) {
 
 		/* print top --> hint */
@@ -100,4 +126,7 @@ void DisplayStack(Stack *stack) {
 }
 
 void DestroyStack(Stack *stack) {
+	free(stack->data);
+	stack->size = 0;
+	stack->top = -1;
 }