Im so close and Im stumped

[jturner38]

Write a program in C++ that checks various lines of text (taken as arithmetical expressions) to see if the following 3 pairs of grouping symbols: '(', ')'; '[', ']'; '{', '}' are being used properly.

You must use a Stack with the array implementation using a class

Test program on the following:

a+b
(a-b)
((c-d)
[(a-b)*(c+d)]
(e+f]
(f+g))
[f-g}
{c+d)
{a*[(c-d)*(e+f)+(g-h)/(f+g)]+h}*b+c
(((((a)))))

#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);
	}

if(Closer(s)){
	S.pop(s);
}

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

I know I should take whatever I pop off the stack and then have Match check to see if if their are matches for each closer I pop. When I compile it just gives me everything is used properly which is incorrect.

[ProgramArtist]

The line

    if(Match)

is for sure not what you want.

gcc says: "warning: the address of `bool Match(char, char)', will always evaluate as `true'"

and IMHO it's right.

"if (Match)" checks if Match is different from zero. Match is a function and you'll check the adress of the function here (which will always be different from zero).

If you want to call Match use brackets ( ) and parameters.

With regards
Programartist

[jturner38]

Ok I finally figured it out. Thanks for the help. Now the problem is that it always displays "Unmatched grouping symbols".

#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";
}
}

[GCDEF]

Use the debugger to step through the Match function to see what it's doing.