Balanced Parenthesis in C

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

// Define a structure for the stack
struct Stack {
    char data;
    struct Stack* next;
};

// Function to create a new stack node
struct Stack* newNode(char data) {
    struct Stack* stackNode = (struct Stack*)malloc(sizeof(struct Stack));
    stackNode->data = data;
    stackNode->next = NULL;
    return stackNode;
}

// Function to check if a character is an opening parenthesis
bool isOpeningParenthesis(char ch) {
    return (ch == '(' || ch == '{' || ch == '[');
}

// Function to check if two characters form a matching pair of parentheses
bool areMatching(char opening, char closing) {
    return ((opening == '(' && closing == ')') ||
            (opening == '{' && closing == '}') ||
            (opening == '[' && closing == ']'));
}

// Function to check for balanced parentheses in an expression
bool isBalanced(char expression[]) {
    struct Stack* stack = NULL;

    for (int i = 0; expression[i]; i++) {
        if (isOpeningParenthesis(expression[i])) {
            struct Stack* newNode = newNode(expression[i]);
            newNode->next = stack;
            stack = newNode;
        } else {
            if (stack == NULL || !areMatching(stack->data, expression[i])) {
                return false;
            }
            struct Stack* temp = stack;
            stack = stack->next;
            free(temp);
        }
    }

    return (stack == NULL);
}

int main() {
    char expression[100];

    printf("Enter an expression: ");
    fgets(expression, sizeof(expression), stdin);

    if (isBalanced(expression)) {
        printf("The expression has balanced parentheses.\n");
    } else {
        printf("The expression does not have balanced parentheses.\n");
    }

    return 0;
}