简介

此模块为学校数据结构必修课学习内容的记录与分享

全文大体分为一下几个部分

• 前言
• 背景
• 分析（伪代码部分）
• 代码
• 结果
• Points

前言

由于前段时间赶团队培训进度，后面需要对培训内容进行总结，因此以后相当一部分时间在 homework 上面的时间可能会减少，因此先贴出主要思路及要点，后面抽时间进行细节补充与整理

又挖坑了…QAQ

背景

在计算机语言编程当中，对称的中括号代表一个完整的变量作用域，其它的括号也有其特殊作用。因此，括号匹配是最基本也最重要的一个语法检查问题，在这一节将使用新学习到的栈数据结构，实现括号匹配机制。

分析：

括号分为左括号和右括号，右括号必须拥有与之对应的左括号，因此我们可以先存储左括号，当遇到右括号时进行弹栈，判断是否匹配，再进行进一步输出。

// 伪代码：
// 判断输入符号
// 左括号 - 储存
// 右括号 - 弹栈
    // 弹栈的左括号匹配 - 继续循环操作
    // 弹栈的左括号不匹配 - 返回错误信息
// 返回正确匹配信息

代码

#include <stdbool.h>
#include <stdio.h>
#include <malloc.h>

#define STACK_MAX_SIZE 10

/**
 * Linear stack of integers. The key is data.
 */
typedef struct CharStack {
    int top;

    char data[STACK_MAX_SIZE]; //The maximum length is fixed.
} *CharStackPtr;

/**
 * Output the stack.
 */
void outputStack(CharStackPtr paraStack) {
    for (int i = 0; i <= paraStack->top; i ++) {
        printf("%c ", paraStack->data[i]);
    }// Of for i
    printf("\r\n");
}// Of outputStack

/**
 * Initialize an empty char stack. No error checking for this function.
 * @param paraStackPtr The pointer to the stack. It must be a pointer to change the stack.
 * @param paraValues An int array storing all elements.
 */
CharStackPtr charStackInit() {
	CharStackPtr resultPtr = (CharStackPtr)malloc(sizeof(struct CharStack));
	resultPtr->top = -1;

	return resultPtr;
}//Of charStackInit

/**
 * Push an element to the stack.
 * @param paraValue The value to be pushed.
 */
void push(CharStackPtr paraStackPtr, int paraValue) {
    // Step 1. Space check.
    if (paraStackPtr->top >= STACK_MAX_SIZE - 1) {
        printf("Cannot push element: stack full.\r\n");
        return;
    }//Of if

    // Step 2. Update the top.
	paraStackPtr->top ++;

	// Step 3. Push element.
    paraStackPtr->data[paraStackPtr->top] = paraValue;
}// Of push

/**
 * Pop an element from the stack.
 * @return The popped value.
 */
char pop(CharStackPtr paraStackPtr) {
    // Step 1. Space check.
    if (paraStackPtr->top < 0) {
        printf("Cannot pop element: stack empty.\r\n");
        return '\0';
    }//Of if

    // Step 2. Update the top.
	paraStackPtr->top --;

	// Step 3. Pop element.
    return paraStackPtr->data[paraStackPtr->top + 1];
}// Of pop

/**
 * Test the push function.
 */
void pushPopTest() {
    printf("---- pushPopTest begins. ----\r\n");
    char ch;
    
	// Initialize.
    CharStackPtr tempStack = charStackInit();
    printf("After initialization, the stack is: ");
	outputStack(tempStack);

	// Pop.
	for (ch = 'a'; ch < 'm'; ch ++) {
		printf("Pushing %c.\r\n", ch);
		push(tempStack, ch);
		outputStack(tempStack);
	}//Of for i

	// Pop.
	for (int i = 0; i < 3; i ++) {
		ch = pop(tempStack);
		printf("Pop %c.\r\n", ch);
		outputStack(tempStack);
	}//Of for i

    printf("---- pushPopTest ends. ----\r\n");
}// Of pushPopTest

/**
 * Is the bracket matching?
 * 
 * @param paraString The given expression.
 * @return Match or not.
 */
bool bracketMatching(char* paraString, int paraLength) {
	// Step 1. Initialize the stack through pushing a '#' at the bottom.
    CharStackPtr tempStack = charStackInit();
	push(tempStack, '#');
	char tempChar, tempPopedChar;

	// Step 2. Process the string.
	for (int i = 0; i < paraLength; i++) {
		tempChar = paraString[i];

		switch (tempChar) {
		case '(':
		case '[':
		case '{':
			push(tempStack, tempChar);
			break;
		case ')':
			tempPopedChar = pop(tempStack);
			if (tempPopedChar != '(') {
				return false;
			} // Of if
			break;
		case ']':
			tempPopedChar = pop(tempStack);
			if (tempPopedChar != '[') {
				return false;
			} // Of if
			break;
		case '}':
			tempPopedChar = pop(tempStack);
			if (tempPopedChar != '{') {
				return false;
			} // Of if
			break;
		default:
			// Do nothing.
			break;
		}// Of switch
	} // Of for i

	tempPopedChar = pop(tempStack);
	if (tempPopedChar != '#') {
		return false;
	} // Of if

	return true;
}// Of bracketMatching

/**
 * Unit test.
 */
void bracketMatchingTest() {
	char* tempExpression = "[2 + (1 - 3)] * 4";
	bool tempMatch = bracketMatching(tempExpression, 17);
	printf("Is the expression '%s' bracket matching? %d \r\n", tempExpression, tempMatch);


	tempExpression = "( )  )";
	tempMatch = bracketMatching(tempExpression, 6);
	printf("Is the expression '%s' bracket matching? %d \r\n", tempExpression, tempMatch);

	tempExpression = "()()(())";
	tempMatch = bracketMatching(tempExpression, 8);
	printf("Is the expression '%s' bracket matching? %d \r\n", tempExpression, tempMatch);

	tempExpression = "({}[])";
	tempMatch = bracketMatching(tempExpression, 6);
	printf("Is the expression '%s' bracket matching? %d \r\n", tempExpression, tempMatch);


	tempExpression = ")(";
	tempMatch = bracketMatching(tempExpression, 2);
	printf("Is the expression '%s' bracket matching? %d \r\n", tempExpression, tempMatch);
}// Of bracketMatchingTest

/**
 The entrance.
 */
void main() {
	// pushPopTest();
	bracketMatchingTest();
}// Of main

结果

Is the expression '[2 + (1 - 3)] * 4' bracket matching? 1
Is the expression '( )  )' bracket matching? 0
Is the expression '()()(())' bracket matching? 1
Is the expression '({}[])' bracket matching? 1
Is the expression ')(' bracket matching? 0
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