Data structure C code 3.2: Application of stack -- bracket matching

Summary : Bracket matching makes people's perception of the stack instantly improve. You will be amazed by the stack in the future.

1. Code (version 2022)

Code first, then nonsense.

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

#define STACK_MAX_SIZE 10

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

    int 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 poped 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. Push element.
    return paraStackPtr->data[paraStackPtr->top + 1];
}// Of pop

/**
 * Test the push function.
 */
void pushPopTest() {
    printf("---- pushPopTest begins. ----\r\n");

	// Initialize.
    CharStackPtr tempStack = charStackInit();
    printf("After initialization, the stack is: ");
	outputStack(tempStack);

	// Pop.
	for (char 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 true;
	} // 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

2. Running results

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
Press any key to continue

3. Code Description

1. On the basis of the data structure C code 5: stack code, directly add a matching function and a test function. For the sake of completeness, they are all put here.
2. This code is also copied and modified from 300 lines (11-20 days, linear data structure) of Rylu Java. The conversion between Java and C is very convenient. The logic of the data structure is consistent for any language, and Java and C Most of the keywords used in C are also consistent.
3. Short strings can be observed with the naked eye. For strings with a length of 20, humans might as well learn from computers and animate a stack by hand.

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