post  Stack-Based Calculator

nubieprogrammer (1)   Link to this post
I am writing a programmer for a basic C++ class that uses a 2 stacks in order to evaluate an equation. I have everything in order and even saw my teacher a couple of times and he helped me. But the problem is that whenever I input, nothing happens. It simply just either waits for me to type something else, or gives me a core dump error. Any Ideas? Here is the code.
#include "linkedStack.h"
#include <iostream>
#include <cmath>
#include <stdlib.h>
#include <string.h>
using namespace std;


struct operatorStruct
{
string op;
int precedence;
};


linkedStack<operatorStruct> operatorStack;
linkedStack<int> operandStack;

bool isoperator(string);
int getprecedence(string);
int calculate();

//Main Function
main()
{

cout<< "please enter an expression" << endl;





calculate();
return 0;
}

bool isoperator(string op)
{
if(op=="+"||op=="-"||op=="*"||op=="/")
{
return true;
}
return false;
}

int getprecedence(string op)
{
if(op=="+"||op=="-")
{
return 1;
}

else if(op=="*"||op=="/")
{
return 2;
}
}



int calculate()
{ string token;
cin >> token;
operatorStruct NewOp;
while(token != ";")
{
if(isdigit(token[0]))
{
int a=atoi(token.c_str());
operandStack.push(a);
}
else if(isoperator(token))
{
NewOp.op=token;
NewOp.precedence=getprecedence(token);



while(operatorStack.empty() != 0 &&
operatorStack.top().precedence >=
NewOp.precedence)
{
int num1=operandStack.top();
operandStack.pop();
int num2=operandStack.top();
operandStack.pop();
if(operatorStack.top().op =="*")
{
operatorStack.pop();
operandStack.push(num2*num1);
}
else if(operatorStack.top().op=="+")
{
operatorStack.pop();
operandStack.push(num2+num1);
}
else if(operatorStack.top().op=="-")
{
operatorStack.pop();
operandStack.push(num2-num1);
}
else if(operatorStack.top().op=="/")
{
operatorStack.pop();
operandStack.push(num2/num1);
}
}
operatorStack.push(NewOp);
}
}
int result= operandStack.top();
cout << result << endl;
}
tomao (31)   Link to this post
could you please put your code in nice code boxes.
It makes it so much easier to read.
magicalblender (82)   Link to this post
Allow me to indent that for you :-)

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#include "linkedStack.h"
#include <iostream>
#include <cmath>
#include <stdlib.h>
#include <string.h>
using namespace std;


struct operatorStruct
{
	string op;
	int precedence;
};


linkedStack<operatorStruct> operatorStack;
linkedStack<int> operandStack;

bool isoperator(string);
int getprecedence(string);
int calculate();

//Main Function
main()
{
	cout<< "please enter an expression" << endl;
	calculate();
	return 0;
}

bool isoperator(string op)
{
	if(op=="+"||op=="-"||op=="*"||op=="/")
	{
		return true;
	}
	return false;
}

int getprecedence(string op)
{
	if(op=="+"||op=="-")
	{
		return 1;
	}
	else if(op=="*"||op=="/")
	{
		return 2;
	}
}



int calculate()
{
	string token;
	cin >> token;
	operatorStruct NewOp;
	while(token != ";")
	{
		if(isdigit(token[0]))
		{
			int a=atoi(token.c_str());
			operandStack.push(a);
		}
		else if(isoperator(token))
		{
			NewOp.op=token;
			NewOp.precedence=getprecedence(token);
			while(operatorStack.empty() != 0 && operatorStack.top().precedence >= NewOp.precedence)
			{
				int num1=operandStack.top();
				operandStack.pop();
				int num2=operandStack.top();
				operandStack.pop();
				if(operatorStack.top().op =="*")
				{
					operatorStack.pop();
					operandStack.push(num2*num1);
				}
				else if(operatorStack.top().op=="+")
				{
					operatorStack.pop();
					operandStack.push(num2+num1);
				}
				else if(operatorStack.top().op=="-")
				{
					operatorStack.pop();
					operandStack.push(num2-num1);
				}
				else if(operatorStack.top().op=="/")
				{
					operatorStack.pop();
					operandStack.push(num2/num1);
				}
			}
			operatorStack.push(NewOp);
		}
	}
	int result= operandStack.top();
	cout << result << endl;
}


hmm. I've never heard of LinkedStack.h before. Did you write it yourself?

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