Check for balanced parentheses in an expression

parenthesisChecker.cpp

/*
Given an expression string exp , write a program to examine whether 
the pairs and the orders of “{“,”}”,”(“,”)”,”[“,”]” are correct in exp. 
For example, the program should print true for exp = “[()]{}{[()()]()}” 
and false for exp = “[(])”

  By : Varun Thakur
  Date : 31/07/2017
*/
#include <stack>
#include <iostream>
using namespace std;

bool isMatchingPair(char a, char b){
    if(a == '[' && b == ']')
        return 1;
    if(a == '{' && b == '}')
        return 1;
    if(a == '(' && b == ')')
        return 1;
    
    return 0;
}
bool parenthesisChecker(string str)
{
    stack<char> s;
    
    for(auto i:str)
    {
        if(i=='['||i=='{'||i=='(')
            s.push(i);
        if(i==']'||i=='}'||i==')') 
        {
            if(s.empty())
                return 0;
            else 
            {
                char ch = s.top();
                s.pop();
                if(!isMatchingPair(ch,i))
                    return 0;
            }
                
        }
    }
    
    return s.empty();
}
int main() {
	//code
	int t;cin>>t;
	while(t--){
	    string s;cin>>s;
	    parenthesisChecker(s)?cout<<"balanced\n":cout<<"not balanced\n";
	}
	return 0;
}