Check Parenthesis C++

[Sebastian Kurpiel]

What's up guys, I have tried to write code to check if an equation has balanced parenthesises my code outputs the equation but it doesn't check if the parenthesises are balanced. These were the goals of my professor 

• In class lab called Parenthesis Checker
• Write an algorithm to check if we have all the parenthesis in an equation
• You will be using a stack of type char in order to do this
• You will use a string to capture the equation to see if it is balanced

#include <iostream>
#include <stack>
#include <string>

using namespace std;

bool check_parenthesis(string equation) {
    char holder;
    stack<char> par_holder;
    for (int i = 0; i<equation.length(); i++) {
        holder = equation[i];
        cout << "Test:" << holder << endl;
        //Please right the algorithm in order to see if parenthesis are correct
        if (equation[i] == '(')
        {
            par_holder.push(equation[i]);
        }
        else if (equation[i] == ')')
        {
            if (par_holder.empty())
                return false;
            else
                par_holder.pop();
        }
    }
    return true;
}


int main() {
    string equation;
    while (equation != "q") {
        cout << "Please enter an equation or q to quit: ";
        //Please have write tthe outcomes correctly, like that of the example output
        cout << "please enter an equation" << endl;
        cin >> equation;
        check_parenthesis(equation);
    }
    return 0;
}

 

[fizzlesticks]

34 minutes ago, Sebastian Kurpiel said:

but it doesn't check if the parenthesises are balanced. 

check_parenthesis(equation);

You are checking if the parenthesis are balanced, your're just never printing out the result.

 

[Sebastian Kurpiel]

14 hours ago, fizzlesticks said:

check_parenthesis(equation);

You are checking if the parenthesis are balanced, your're just never printing out the result.

 

 

Where would I  add the cout << "balanced!" part? I have tried everywhere and I'm still receiving errors...

[fizzlesticks]

3 hours ago, Sebastian Kurpiel said:

Where would I  add the cout << "balanced!" part? I have tried everywhere and I'm still receiving errors...

You'd have to check the return value from check_parenthesis

if(check_parenthesis(equation))
{
	//parenthesis are balanced
}
else
{
	//not balanced
}

 

[patrickjp93]

std::count_if()

 

You'll need to write a custom increment/decrement lambda, but this is trivial.