Thread: Help: Storing tokenized 2-digit char (infix->postfix converter)

Hi,

I'm trying to store a tokenized cstring (consisting of a mathematical expression) into a templated char stack. However, when I print the contents of the stack, the char tokens that represented 2-digit int were cut off after the first digit. Here's an example:

Code:

Input:    12 + 14
Output:  1 + 1

I expected this. Can I get help trying to store 2-digit tokens into the stack? Perhaps convert it so I can use the tokens later to calculate in RPN?

Here's the code that stores a cstring into the stack:

Code:

void Stack<E>::str2Stack(char cstring[])
{
	char* token;
	token = strtok(cstring, " \n");
	while (token != NULL)
	{
		push(*token);
		cout<<"Token "<<token<<" pushed"<<endl;
		token = strtok(NULL, " \n");
	}
}

Thank you!

Originally Posted by AndrewHunter

You are going to need to know about the Shunting yard Algorithm

I read up on it before the project, and I incorporated it into my program.

Originally Posted by AndrewHunter

Char arrays should be avoided, you could use std::string here instead. Strtok is a C function, you should be using std::stringstream for tokenizing

This was my first thought. I turned to c strings as a suggestion from the professor, though.

Originally Posted by AndrewHunter

Unless you are required to create your own stack class, use std::stack.

I was.


Here is my infix->postfix function

Code:

template <typename E>
Stack<E> Stack<E>::infix2Post() throw(MismatchedParen)
{
	Stack<char> opStk(50);
	Stack<char> outStk(50);
	int i=0; 

	while(isOperator(S[i])||isOperand(S[i])||S[i]=='('||S[i]==')')
	{
		if(isOperand(S[i]))
		{
			outStk.push(S[i]);
			i++;
		}
		if(isOperator(S[i]))
		{	
			while((!opStk.empty())&&((S[1]!='^'&& precedence(S[i])<=precedence(opStk.top()))||
				(S[1]=='^'&&precedence(S[i])<precedence(opStk.top()))))

				{
					outStk.push(opStk.top());
					opStk.pop();
				}
			opStk.push(S[i]);
			i++;
		}

		if(S[i]=='(')
		{
			opStk.push('(');
			i++;
		}

		if(S[i]==')')
		{
			while(opStk.top()!='(')
			{
				outStk.push(opStk.top());
				opStk.pop();
			}

			if(opStk.top()=='(')
			{
				opStk.pop();
				i++;	
			}

			if(opStk.empty())
				throw MismatchedParen("No closing parenthesis");

	
		}

	}

	while(!(opStk.empty()))
	{
		if(opStk.top()=='(' || opStk.top()==')')
			throw MismatchedParen("No closing parenthesis");
		outStk.push(opStk.top());
		opStk.pop();
	}

	return outStk;

}

And my driver:

Code:

#include <iostream>
#include"Stack.h"
#include"Stack.cpp"				
#include"Exception.h"
#include<string>
#include<cstring>
#include<cstdlib>
using namespace std;

#pragma warning( disable : 4290 )

int main()
{	
	char infix[50];
	char temp[50];
	
	Stack<char> inStk(50);


	cout<<"Enter an expression: ";
	cin.getline (infix, 50, '\n' );

	strcpy(temp, infix);

	cout<<infix<<endl;

	cout<<"NOW PRINTING LOCAL INFIX CHAR ARRAY"<<endl;
	char* token=NULL;
	token = strtok(temp, " \n");
	while (token != NULL)
	{
		cout<<token<<endl;
		token = strtok(NULL, " \n");
	}

	strcpy(temp, infix);

	cout<<"\nNOW PUSHING INFIX CHAR ARRAY TO INFIXSTACK CLASS ARRAY"<<endl;
	inStk.str2Stack(temp);

	cout<<"\n\nNOW PRINTING INFIXSTACK CLASS ARRAY"<<endl;

	inStk.printStack();

	strcpy(temp, infix);

	cout<<"\n\nNOW COPYING INFIXSTACK CLASS ARRAY TO POSTFIXSTACK CLASS ARRAY"<<endl;

	Stack<char> postStk(50);

	postStk=inStk;
	
	postStk.printStack();

	cout<<"\n\nNOW CONVERTING INFIXSTACK CLASS ARRAY TO POSTFIXSTACK CLASS ARRAY"<<endl;

	postStk=inStk.infix2Post();

	cout<<"\n\nNOW PRINTING POSTFIXSTACK CLASS ARRAY"<<endl;
	postStk.printStack();

	cout<<"\n\nNOW PRINTING EVALUATING POSTFIXSTACK CLASS ARRAY"<<endl;
	cout<<postStk.evalPost()<<endl;
	return 0;
}