stack in C++

drakon

SAn schrieb:

Hey, people!
...

Hi.
Ah nice to know. I googled it, but i couldn't find anything good about a "stack-rechner".
And I think the OP also didn't know it clear enough to explain us the situation.

But it's not a problem to change the calculator to this functionability.

SAn

Here is the solution I wrote in 20 minutes (without any error checking and so on):

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

using namespace std;

typedef stack<double> TStack;

inline double Pop(TStack& Stack)
{
	double result(Stack.top());
	Stack.pop();
	return result;
}

inline double StringToDouble(string const &String)
{
	istringstream Stream(String);
	double result;
	Stream>>result;
	return result;
}

int main(int argc, char **argv)
{
	TStack Stack;
	string Input;

	while(true)
	{
		cin>>Input; if(Input[0]=='.') break;

		switch(Input[0])
		{
			case '+': Stack.push(Pop(Stack)+Pop(Stack)    ); break;
			case '-': Stack.push(-Pop(Stack)+Pop(Stack)   ); break;
			case '/': Stack.push(1.0/Pop(Stack)*Pop(Stack)); break;
			case '*': Stack.push(Pop(Stack)*Pop(Stack)    ); break;
			default: Stack.push(StringToDouble(Input));
		}

		cout<<"Result: "<<Stack.top()<<endl;
	};

	cout<<"Done"<<endl;

	return EXIT_SUCCESS;
}

Here is the result:

2
Result: 2
3
Result: 3
+
Result: 5
4
Result: 4
5
Result: 5
+
Result: 9
*
Result: 45
.
Done

You can also enter input in one line using spaces:

2 3 + 4 5 + * .
Result: 2
Result: 3
Result: 5
Result: 4
Result: 5
Result: 9
Result: 45
Done

SAn schrieb:

2 3 + 4 5 + *

Hi Brother !
Thats RPN (Reverse Polish Notation by Jan Lukasiewicz) isnt it ?
I wrote such a calculator/parser last year^^

SAn

Big Brother schrieb:

Hi Brother !
Thats RPN (Reverse Polish Notation by Jan Lukasiewicz) isnt it ?
I wrote such a calculator/parser last year^^

Yes, that is RPN. And the "stack computer" is the simple parser which can process RPN.