平衡括号

Question

我想平衡括号，但我不太明白。输入括号时我也遇到了一些错误，有时它会接受输入。 这是我的代码：

#include <iostream>
#include <string>
#include <vector>
#include <stack>
using namespace std;


int main()
{
    string x;
    stack < char, vector<char> > iStack;
    
    cout << "Enter series of parentheses: ";
    getline(cin, x);
    
    for (int i=0; i<x.length(); i++)
      if (x[i] == '(' || x[i] == '{' || x[i] == '[')
          iStack.push(x[i]);
      else
      {  
        cout << iStack.top() << endl;
        iStack.pop();
      }  
    
    if (iStack.empty())
        cout << "Balance!" << endl;
    else
        cout << "Not Balance!" << endl;
}