I can't figure out why

The only problem Im having is that my program always displays "Unmatched grouping symbols". I know its in my main program in my while loop. I just cant figure out what's causing it. I've tried to use the Debugger but I dont understand what too look for.

Code:

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#include <iostream>
using namespace std;

const int DefaultListSize = 50;
typedef char Elem;

class Astack
{
private:
        int top;        /*Index for top element*/
        int size;        /*Maximum size of stack*/
        Elem*listArray;        /*Array holding stack elements*/
public:       
                Astack(int sz =DefaultListSize)        /*Constructor*/
                {size = sz; top = 0; listArray = new Elem[sz];}
                ~Astack() { delete [] listArray;}        /*Destructor*/
                void clear() {top = 0;}
                bool push(const Elem& item){
                        if(top == size) return false;        /* Stack is full*/
                        else {listArray [top++] = item;
                                return true;
                        }
                }
                bool pop(Elem& item){        /*Pop top element*/
                        if(top == 0) return false;
                        else {item = listArray[--top];
                                return true;
                        }
                }
                bool topValue(Elem& item) const {        /*Return top element*/
                        if (top == 0) return false;
                        else {item = listArray[top - 1];
                        return true;
                        }
                }
                int length() const {return top;}
                bool IsEmpty() const {if(top == 0) return true;
                else return false;
                }
        };

        bool Opener(char ch){
        if((ch == '(') || (ch =='[') || (ch =='{'))
                return true;
        else
                return false;
        }/*end of opener*/

        bool Match(char Lc, char Rc){
                if(( Lc == '(') && (Rc == ')') || ((Lc == '[') && (Rc == ']')) ||((Lc == '{') && (Rc == ']')))
                        return true;
                else
                        return false;
        }/*end of Match*/

        bool Closer(char ch){
                if((ch == ')') || (ch == ']') || (ch == '}'))
                        return true;
                else
                        return false;
        }/*end of closer*/

int main(){
       
        Astack S;
        char s;

cout <<"Enter data:";
cin >> s;

if(Opener(s)){
        S.push (s);
        }
else
        cin.ignore(s);

if(Closer(s)){
        S.pop(s);
}

while(S.pop(s)){
        if(Match(Opener(s), Closer(s)))
                cout << "Grouping symbols used properly";
       
        else
                cout << "Unmatched grouping symbols";
}

}

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Match() takes 2 chars, but you are passing in 2 bools instead.

Oh I think I know what u mean

Code:

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while(S.pop(s)){
        if(Match('(', ')') || ('[', ']') || ('{', '}'))
                cout << "Grouping symbols used properly";
       
        else
                cout << "Unmatched grouping symbols";
}

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The problem with this tho is that it always displays "Grouping symbols used properly". So maybe I need &&'s instead of ||'s?

I changed it to this but Im still having the same problem. Is it because Im missing a part that somehow suppose to compare how many openers and closers I have. Which means if I have at least 1 or more than the other than I will display "Unmatched grouping symbols" ?

Code:

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while(S.pop(s)){
        if(Match('(',')') || Match('[', ']') || Match('{', '}'))
                cout << "Grouping symbols used properly";
       
        else
                cout << "Unmatched grouping symbols";
}

---

You pop a character.
If it's a (, then you need to match it with a )
It's no good trying to match it with a ]

Oooh wait let me see...so instead of saying S.pop(s)...should it be S.pop(')') then check it in to see if its a match? When u say You pop a CHARACTER...u mean what Im actually poppin off the stack right?

Yes, pop() returns (via the reference parameter), the character at the top of the stack.

So if you're looking at a ) in your string, you should be expecting to pop a (

Ok I think I see what u mean but isnt a rule for the Stack first one in is the last one out? So wouldnt I always pop a Closer? I tried this:

Code:

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S.pop('(');

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But I get an error: initial value of reference to non-const must be an lvalue. An lvalue means you can use the object on the left of an assignment operator correct? If thats true then what would I assign the bracket to?

You pop into a variable, then compare two things...

I got it finally. Here my final code if anybody wants to check it out:

Code:

---

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


const int DefaultListSize = 50;
typedef char Elem;

class Astack
{
private:
        int top;        /*Index for top element*/
        int size;        /*Maximum size of stack*/
        Elem*listArray;        /*Array holding stack elements*/
public:       
                Astack(int sz =DefaultListSize)        /*Constructor*/
                {size = sz; top = 0; listArray = new Elem[sz];}
                ~Astack() { delete [] listArray;}        /*Destructor*/
                void clear() {top = 0;}
                bool push(const Elem& item){
                        if(top == size) return false;        /* Stack is full*/
                        else {listArray [top++] = item;
                                return true;
                        }
                }
                bool pop(Elem& item){        /*Pop top element*/
                        if(top == 0) return false;
                        else {item = listArray[--top];
                                return true;
                        }
                }
                bool topValue(Elem& item) const {        /*Return top element*/
                        if (top == 0) return false;
                        else {item = listArray[top - 1];
                        return true;
                        }
                }
                int length() const {return top;}
                bool IsEmpty() const {if(top == 0) return true;
                else return false;
                }
        };

        bool Opener(char ch){
        if((ch == '(') || (ch =='[') || (ch =='{'))
                return true;
        else
                return false;
        }/*end of opener*/

        bool Match(char Lc, char Rc){
                if(( Lc == '(') && (Rc == ')') || ((Lc == '[') && (Rc == ']')) ||((Lc == '{') && (Rc == '}')))
                        return true;
                else
                        return false;
        }/*end of Match*/

        bool Closer(char ch){
                if((ch == ')') || (ch == ']') || (ch == '}'))
                        return true;
                else
                        return false;
        }/*end of closer*/


int main(){
       
        Astack S;
        string s;
        unsigned int i;
        char a;

        cout <<"Enter data:\n";
        getline(cin, s);

        for(i = 0; i < s.length(); i++){
                if(Opener(s.at(i)))
                        S.push(s.at(i));

                else if(Closer(s.at(i))){
                        if(S.IsEmpty()){
                                cout << "Found a Closing bracket before an Opening bracket or\n There are no Opening brackets or\n There's an extra Closing bracket";
                                cout << "\nGrouping symbols not used properly";
                                return 0;
                        }
                        else
                                S.pop(a);
                                if(!Match(a, s.at(i))){
                                        cout << "No matching bracket\n";
                                        cout << "Grouping symbols not used properly";
                                        return 0;
                                }               
                }
        }
        if(!S.IsEmpty()){
                cout << "There's still an Opening bracket\n";
                cout << "Grouping symbols not used properly";
        }
        else
                cout << "Grouping symbols were used properly";
        return 0;
}

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