check.cpp

#include <ctime>
#include <cstdlib>
#include <iostream>
#include <string>
#include <stack>

bool isOpenBracket(char symbol) {
    return symbol == '(' || symbol == '{' || symbol == '[';
}

bool isClosingBracket(char symbol) {
    return symbol == ')' || symbol == '}' || symbol == ']';
}

char getOpenBracketPair(char bracket) {
    return (bracket == '}') ? '{' : (bracket == ')') ? '(' :
        (bracket == ']') ? '[' : '\0';
}

bool areParenthesesGood(const std::string &source) {
    std::stack<char> stack;
    for (size_t i = 0; i < source.size(); ++i) {
        if (isOpenBracket(source[i])) {
            stack.push(source[i]);
        }
        else {
            if (isClosingBracket(source[i])) {
                char openBracket = getOpenBracketPair(source[i]);
                if (!stack.empty() && stack.top() == openBracket) {
                    stack.pop();
                }
                else {
                    return false;
                }
            }
        }
    }
    
    if (!stack.empty())
        std::cout << "unexpected " << stack.top() << std::endl;

    return stack.empty();
}

int main(int argc, char *argv[]) 
{
    srand(time(0));

    std::string expression = "{{((x+(g-[f+h]*c)-(q+w)))}}";
    std::cout << areParenthesesGood(expression) << std::endl;

    std::cin.get();
    return 0;
}