Thread: Question about cin function

Hi dudes,
i have a problem in using cin function.
i've written code for checking parantheses Balance,
it works only for non-empty strings, but doesn't work for empty strings.
however i know the problem is coming from cin function, but i can't handle it!
here is a part of my code,
thanks in advance, for any help

Code:

int main()
{
	int n; 
	cin>>n;
	string st;
	vector<string> vct;
	
	while(n!=0)
	{
		cin>>st;
		if (st.empty())
		{
			//string is empty and Balanced
			//n--;
		}


		else
		{
      if(checkBalanced(st))
		vct.push_back("Yes");
	  else	
		vct.push_back("No"); 
	   n--;
		}
	}
	for (int i=0 ; i<vct.size() ; i++)
		cout << vct.at(i) << endl;
	
	return 0;
}

i mean when the user pressed Enter (empty string), the program goes to newline! like that you do not anything , so here is my full code.

Code:

#include<iostream>
#include<stack>
#include<string>
#include <vector>
#include <stdio.h>
using namespace std;
bool ArePair(char opening,char closing)
{
	if(opening == '(' && closing == ')') return true;
	else if(opening == '[' && closing == ']') return true;
	return false;
}
bool checkBalanced(string st)
{
	stack<char>  S;
	for(int i =0 ; i<st.length() ; i++)
	{
		if(st[i] == '(' || st[i] == '[')
			S.push(st[i]);
		else if(st[i] == ')' || st[i] == ']')
		{
			if( (S.empty() ) || !ArePair(S.top(),st[i]))
				return false;
			else
				S.pop();
		}
	}
	return S.empty() ? true:false ;
}




int main()
{
	int n; 
	cin>>n;
	string st;
	vector<string> vct;
	
	while(n!=0)
	{
		cin>>st;
		if (st.empty())
		{
			//string is empty and Balanced
			//n--;
		}


		else
		{
      if(checkBalanced(st))
		vct.push_back("Yes");
	  else	
		vct.push_back("No"); 
	   n--;
		}
	}
	for (int i=0 ; i<vct.size() ; i++)
		cout << vct.at(i) << endl;
	
	return 0;
}

clue 1: cin>> the (c in) function with the input operators, are used to have an operator input a variable.
clue 2: you have cin>> in the area of int main where variables a usually declared.
clue 3: n has not value until you give it one.

one thing that really bothered me while reading this thread:
cin is not a function , it's an object.
it's >> operator was overloaded to provide functionality. still , it's an object and not a function.