Creating a Reverse Polish calculator in C++ - c++

Assignment: For this assignment, you are to write a program, which will calculate the results of Reverse Polish expressions that are provided by the user.
You must handle the following situations (errors):
Too many operators (+ - / *)
Too many operands (doubles)
Division by zero
The program will take in a Polish expression that separates the operators and operands by a single space, and terminates the expression with an equals sign.
The program will continue to take and evaluate expressions until the user enters a zero (0) on a line by itself followed by a new line.
Problem 1: I am having a problem with telling the user that there are too many operators and operands. I tried to code it but I have no
idea where to begin with this.
Problem 2: I want the program to end when the user inputs 0, but it is not doing anything when I do it in my program.
#include<iostream>
#include<iomanip>
#include<string>
#include<sstream>
using namespace std;
class Node
{
double data;
Node *top;
Node *ptr;
public:
Node()
{
top = NULL;
ptr = NULL;
}
bool isEmpty()
{
return top == 0;
}
void pushValue(double val)
{
Node *next = new Node;
next->data = val;
next->ptr = top;
top = next;
}
double popVal()
{
if (isEmpty())
{
cout << "Error: Too many operators" << endl;
}
else
{
Node *next = top->ptr;
double ret = top->data;
delete top;
top = next;
return ret;
}
}
//Displays the answer of the equation
void print()
{
cout << "= " << top->data << endl;
}
};
bool isOperator(const string& input)
{
string ops[] = { "+", "-", "*", "/" };
for (int i = 0; i < 4; i++)
{
if (input == ops[i])
{
return true;
}
}
return false;
}
//This function tells the operators what to do with the values.
void performOp(const string& input, Node& stack)
{
double Val1, Val2;
int errorCheck = 0;
Val1 = stack.popVal();
Val2 = stack.popVal();
if (input == "+")
{
stack.pushValue(Val1 + Val2);
}
else if (input == "-")
{
stack.pushValue(Val1 - Val2);
}
else if (input == "*")
{
stack.pushValue(Val1 * Val2);
}
else if (input == "/" && Val2 != 0)
{
stack.pushValue(Val1 / Val2);
}
if (input == "/" && Val2 == 0)
{
cout << "Error: Division by zero" << endl;
errorCheck = 1;
}
if (errorCheck == 0)
{
stack.print();
}
}
int main()
{
cout << "Reverse Polish Notation Calculator!" << endl;
cout << "-------------------------------------------------------------------" << endl;
cout << "Enter your values followed by your operators(Enter 0 to exit)" << endl;
string input;
Node stack;
//Checks the user's input to see which function to use.
while (true)
{
cin >> input;
double num;
if (stringstream(input) >> num)
{
stack.pushValue(num);
}
else if (isOperator(input))
{
performOp(input, stack);
}
else if (input == "0")
{
return 0;
}
}
}

Related

Areas to improve/change?

I'm not too sure if questions of this sort is allowed on stackoverflow but here it goes. I finished up this assignment to calculate reverse polish expressions with a small set of operators. All the tests passed and I have already submitted the assignment. I was wondering if you guys had any suggestions where I could improve on the code that could be applied to my future assignments/projects.
#include <iostream>
#include <string>
#include <sstream>
using namespace std;
class TheStack
{
public:
void push(double d1);
double pop();
int getNodeTracker();
private:
struct Node
{
double data;
Node* next;
};
Node* bottom = NULL;
Node* top = NULL;
Node* newP = NULL;
int nodeTracker = 0;
};
void TheStack::push(double d1)
{
newP = new Node;
newP->data = d1;
newP->next = NULL;
if (bottom == NULL)
{
bottom = top = newP;
top->next = NULL;
}
else
{
newP->next = top;
top = newP;
}
nodeTracker += 1;
}
double TheStack::pop()
{
Node* tempP;
double tempD;
if (top == NULL)
{
cout << "The stack is empty." << endl;
}
else
{
tempP = top;
tempD = tempP->data;
top = top->next;
delete(tempP);
nodeTracker -= 1;
return(tempD);
}
}
int TheStack::getNodeTracker()
{
return nodeTracker;
}
bool isOperand(string s1);
bool isOperator(string s1);
double operate(string s1, double d1, double d2);
int processor(string str);
bool validString(string str);
int main()
{
// getting user input
string str;
getline(cin, str);
// input loop
while (str != "0")
{
processor(str);
cout << endl;
getline(cin, str);
}
// end program
return 0;
}
bool isOperand(string s1)
{
try
{
stod(s1);
}
catch (...)
{
return false;
}
return true;
}
bool isOperator(string s1)
{
string validOps[4] = { "+", "-", "*", "/" };
for (int i = 0; i < 4; i++)
{
if (s1 == validOps[i])
{
return true;
}
}
return false;
}
double operate(string s1, double d1, double d2)
{
char op = s1[0];
switch (op)
{
case '+':
return d1 + d2;
case '-':
return d1 - d2;
case '*':
return d1 * d2;
case '/':
return d1 / d2;
}
}
bool validString(string str)
{
for (int i = str.size()-1; i >= 0; i--)
{
if (str[i] == '=')
{
return true;
}
}
return false;
}
int processor(string str)
{
TheStack stacklist;
istringstream iss(str);
string streamVar;
iss >> streamVar;
// checks if expression has = sign
if (!validString(str))
{
cout << "Error: Please input valid expression." << endl;
return -1;
}
// builds and operates upon stack
while (streamVar != "=")
{
if (isOperand(streamVar))
{
stacklist.push(stod(streamVar));
}
else if (isOperator(streamVar))
{
if (stacklist.getNodeTracker() > 1)
{
double d2 = stacklist.pop();
double d1 = stacklist.pop();
if (streamVar == "/" && d2 == 0)
{
cout << "Error: Division by 0." << endl;
return -1;
}
double result = operate(streamVar, d1, d2);
stacklist.push(result);
}
else
{
cout << "Error: Too many operators." << endl;
return -1;
}
}
iss >> streamVar;
}
// operand error case
if (stacklist.getNodeTracker() > 1)
{
cout << "Error: Too many operands." << endl;
return -1;
}
// output
cout << stacklist.pop() << endl;
return 0;
}

Unable to compile c++ project in terminal

My assignment is to make a binary expression tree to convert postfix expressions to infix expressions in C++. I originally coded all my work in my Xcode IDE and would periodically ssh to linprog4 in terminal to make sure it works there because it has to before I turn it in. I don't understand the errors that are popping up when I compile it using g++ -o proj4.x -std=c++11 proj4_driver.cpp BET.cpp
This assignment was due 2 weeks ago and unfortunately when I was turning in the tar file with all my files, I forgot to include the .tar extension. I don't think that would affect my files but now they aren't compiling and I don't understand the errors I am getting. Could someone skim through my code and see if I am missing anything? I've looked over my code and it doesn't look like I accidentally typed something randomly somewhere.
Here is a screenshot of the errors I am getting
BET.h
#ifndef BET_H
#define BET_H
using namespace std;
class BET {
private:
struct BinaryNode {
string data;
BinaryNode * parent;
BinaryNode * childLeft;
BinaryNode * childRight;
bool visited; // to tell if node has been visited to or not
// Construct a blank copy version BinaryNode when an
// object of BET is created
BinaryNode( const char & d = char{}, BinaryNode * p = NULL,
BinaryNode * l = NULL,
BinaryNode * r = NULL, bool v = false )
: data { d },
parent { p },
childLeft { l },
childRight { r },
visited { v } {}
// Construct a blank move version of BinaryNode when an
// an object of BET is created
BinaryNode( char && d, BinaryNode * p = NULL, BinaryNode * l = NULL,
BinaryNode * r = NULL, bool v = false )
: data { std::move(d) },
parent { p },
childLeft { l },
childRight { r },
visited { v } {}
}; // end of BinaryNode struct
public:
// constructors and destructor
BET();
BET( const string postfix );
BET( const BET & rhs );
~BET();
// help copy constructor
bool buildFromPostfix( const string postfix );
// copy assignment operator
const BET & operator=( const BET & rhs );
void printInfixExpression();
void printPostfixExpression();
size_t size();
size_t leaf_nodes();
bool empty();
bool isOperand(BinaryNode * n);
private:
BinaryNode *root;
size_t leaves, nodes;
bool useP;
void printInfixExpression( BinaryNode * n );
void makeEmpty( BinaryNode* & t );
BinaryNode * clone( BinaryNode * t ) const;
void printPostfixExpression( BinaryNode * n );
size_t size( BinaryNode * t );
size_t leaf_nodes( BinaryNode * t );
}; // end of BET class
#endif
BET.cpp
#include <iostream>
#include <stack>
#include <sstream>
#include <string>
#include "BET.h"
//using namespace std;
// default zero-param constructor
BET::BET() {
root = new BinaryNode;
leaves = 0;
nodes = 0;
}
// one-param constructor, where parameter "postfix" is a
// string containing a postfix expression. The tree should
// be built based on the postfix expression. Tokens in the
// postfix expression are separated by space
BET::BET(const string postfix) {
root = new BinaryNode;
buildFromPostfix(postfix);
}
// copy constructor
BET::BET(const BET & rhs) {
leaves = rhs.leaves;
nodes = rhs.nodes;
root = rhs.root;
}
// destructor
BET::~BET() {
makeEmpty(root);
leaves = nodes = 0;
}
bool BET::buildFromPostfix(const string postfix) {
// Create stack to hold variables
stack<BinaryNode *> s;
stack<BinaryNode> bet;
char token;
string temp;
int index = 1;
bool doubleDigit = false;
int opCount = 0, digitCount = 0;
//stringstream hexToInt;
// iterator through postfix
for (int i = 0; i < postfix.size(); ++i) {
// grab token at iterations index
token = postfix[i];
if ( (token > '0' && token < '9') || (token > 62 && token < 80)) {
// check to see if token is an operand
// create a dynamic object of BinaryNode
BinaryNode *operand = new BinaryNode;
// check to see if next index of postfix is digit
// if its not, then we know its a double digit
// this while loop should only continue as long as the
// next index is between 0 and 9
temp = postfix[i];
while (postfix[i + index] >= '0' && postfix[i + index] <= '9') {
temp += postfix[i + index];
index++;
doubleDigit = true;
}
if (doubleDigit == true) {
i += index;
doubleDigit = false;
index = 1;
operand->data = temp;
} else {
operand->data = postfix[i];
}
s.push(operand);
digitCount++;
} else if (token == '+' || token == '-' || token == '*' || token == '/'){
// check to see if token is operator
BinaryNode *operand = new BinaryNode;
operand->data = postfix[i];
operand->childLeft = s.top();
s.top()->parent = operand;
s.pop();
operand->childRight = s.top();
s.top()->parent = operand;
s.pop();
s.push(operand);
opCount++;
} else {
// if neither, must be space or other character
if (token == ' ') {
} else
return false;
}
}
if (digitCount <= opCount) {
return false;
}
root = s.top();
nodes = size();
//leaves = leaf_nodes();
// THINGS TO DO:
// Make error cases with if statements to return false at some point
return true;
}
// assignment operator
const BET & BET::operator=(const BET & rhs) {
root = clone(rhs.root);
return *this;
}
// public version of printInfixExpression()
// calls the private version of the printInfixExpression fuction
// to print out the infix expression
void BET::printInfixExpression() {
printInfixExpression(root);
}
// public version of printPostfixExpression()
// calls the private version of the printPostfixExpression function
// to print out the postfix expression
void BET::printPostfixExpression() {
printPostfixExpression(root);
}
// public version of size()
// calls the private version of the size function to return
// the number of nodes in the tree
size_t BET::size() {
return size(root);
}
// public version of leaf_nodes()
// calls the private version of leaf_nodes function to return
// the number of leaf nodes in the tree
size_t BET::leaf_nodes() {
return leaf_nodes(root);
}
// public version of empty()
// return true if the tree is empty. return false otherwise
bool BET::empty() {
if (nodes == 0) {
return true;
} else
return false;
}
// checks whether node is operand or not
bool BET::isOperand(BinaryNode * n) {
if (n->data != "+" && n->data != "-" && n->data != "*" && n->data != "/") {
return true;
} else
return false;
}
// private version of printInfixExpression
// print to the standard output the corresponding infix expression
void BET::printInfixExpression(BinaryNode * n) {
//BinaryNode * temp = NULL;
if (n != NULL ) {
printInfixExpression(n->childRight);
cout << n->data << " ";
printInfixExpression(n->childLeft);
}
/*
if (n != NULL && useP == true) {
printInfixExpression(n->childRight);
if (isOperand(n->parent) && n->parent != NULL && !n->childLeft) {
cout << "(";
}
cout << n->data << " ";
if (isOperand(n->parent) && n->parent != NULL && !n->childRight) {
cout << ")";
}
printInfixExpression(n->childLeft);
}
*/
}
// private method makeEmpty()
// delete all nodes in the subtree pointed to by n.
// Called by functions such as the destructor
void BET::makeEmpty(BinaryNode * & n) {
if (n != NULL) {
makeEmpty(n->childLeft);
makeEmpty(n->childRight);
delete n;
}
}
// private method clone()
// clone all nodes in the subtree pointed by n. Called by
// functions such as the assignment operator=
BET::BinaryNode * BET::clone(BinaryNode * n) const {
if (n != NULL) {
root->childRight = clone(n->childRight);
root->childLeft = clone(n->childLeft);
root->data = n->data;
}
return root;
}
// private method printPostfixExpression()
// print to the standard output the corresponding postfix expression
void BET::printPostfixExpression(BinaryNode * n) {
if (n != NULL) {
printPostfixExpression(n->childRight);
printPostfixExpression(n->childLeft);
cout << n->data << " ";
}
}
// private version of size()
// return the number of nodes in the subtree pointed by n
size_t BET::size(BinaryNode * n) {
if (n != NULL) {
size(n->childLeft);
size(n->childRight);
nodes++;
}
return nodes;
}
// return the number of leaf nodes in the subtree pointed by n
size_t BET::leaf_nodes(BinaryNode * n) {
if (n != NULL) {
leaf_nodes(n->childLeft);
leaf_nodes(n->childRight);
if (n->childLeft == NULL && n->childRight == NULL) {
leaves += 1;
}
}
return leaves;
}
Driver.cpp
#include "BET.cpp"
//using namespace std;
int main() {
string postfix;
// get a postfix expression
cout << "Enter the first postfix expression: ";
getline(cin, postfix);
// create a binary expression tree
BET bet1(postfix);
if (!bet1.empty()) {
cout << "Infix expression: ";
bet1.printInfixExpression();
cout << "\n";
cout << "Postfix expression: ";
bet1.printPostfixExpression();
cout << "\nNumber of nodes: ";
cout << bet1.size() << endl;
cout << "Number of leaf nodes: ";
cout << bet1.leaf_nodes() << endl;
// test copy constructor
BET bet2(bet1);
cout << "Testing copy constructor: ";
//bet2.printInfixExpression();
// test assignment operator
BET bet3;
bet3 = bet1;
cout << "Testing assignment operator: ";
//bet3.printInfixExpression();
}
cout << "Enter a postfix expression (or \"quit\" to quit): ";
while (getline(cin, postfix)) {
if (postfix == "quit") {
break;
}
if (bet1.buildFromPostfix(postfix)) {
cout << "Infix expression: ";
bet1.printInfixExpression();
cout << "Postfix expression: ";
bet1.printPostfixExpression();
cout << "Number of nodes: ";
cout << bet1.size() << endl;
cout << "Number of leaf nodes: ";
cout << bet1.leaf_nodes() << endl;
}
cout << "Enter a postfix expression (or \"quit\" to quit): ";
}
return 0;
}
Driver.cpp #include "BET.cpp" should be #include "BET.h"
Or (and this is just for completeness, not recommended), leave the include of the .cpp, but then only try to compile the one .cpp (as in g++ Driver.cpp) - since driver will include BET and so all your code is there and will build.

RPN using Linked Lists

I am having trouble figuring out an RPN calculator where we have to use Linked List for this assignment. ( I had finished the assignment using the stack<double> method, but It HAS to be using linked lists.
I am having some trouble with the Error checking:
Too many operators (+ - / *)
Too many operands (doubles)
Division by zero
The program is supposed to continue to take and evaluate expressions until the user enters a zero (0) on a line by itself followed by a new line. I am also having some trouble with this. Since I put in my error checking for "too many operands", it
WILL NOT ALLOW ME TO DO A SECOND CALCULATAION , OUTPUT WILL BE "TOO MANY OPERANDS"
I can't seem to get an error check to work for "Too many operators"
I have tried several different things for the required error checking and looked at many other RPN questions on different sites, as you can see through some of the things I tried and commented out.
Any help would be greatly appreciated!
Thanks
#include <iostream>
#include <string>
#include <sstream>
#include <iomanip>
using namespace std;
struct NODE
{
float num;
NODE *next;
};
class stack
{
private:
NODE *head;
public:
stack();
void push(float);
float pop();
int nElements();
float display();
};
class RPN: public stack
{
public:
void add();
void subtract();
void multiply();
void divide();
};
stack::stack()
{
head = NULL;
}
void stack::push(float a_number)
{
NODE *temp = new NODE;
if (temp)
{
temp->num = a_number;
temp->next = head;
head = temp;
}
}
float stack::pop()
{
float number = 0;
if (!head)
{
return 0;
}
else
{
NODE *temp = head;
number = head->num;
head = temp->next;
delete temp;
}
return number;
}
int stack::nElements()
{
int counter=0;
for (NODE *node = head; node; node=node->next)
{
counter++;
}
return counter;
}
float stack::display()
{
//ERROR CHECKING TOO MANY OPERANDS??? PRINTING TOO MANY OPERANDS FOR : 100 10 50 25 / * - -2 / = , but still giving correct output && WILL NOT ALLOW ME TO DO A SECOND CALCULATAION , OUTPUT WILL BE TOO MANY OPERANDS
if(nElements() !=1)
{
cout << "Error: too many operands" << endl;
return 1;
}
/*
// if( nElements() < 2 )
{
cout << "Error: too many operators" << endl;
return 1;
}
*/
else //(nElements() > 0)
{
float temp = pop();
cout << temp << endl;
push(temp);
return temp;
}
}
void RPN::add()
{
if (nElements()>=2)
{
push(pop() + pop());
}
}
void RPN::subtract()
{
if (nElements()>=2)
{
push(0 - pop() + pop());
}
}
void RPN::multiply()
{
if (nElements()>=2)
{
push(pop() * pop());
}
}
int RPN::divide()
{
double op2;
op2 = pop();
if(op2 != 0.0)
{
push(pop() / op2);
}
else
{
cout << "Error: Division by zero.\n"; //??? Still printing output
return -1;
}
}
//Function prototype for isOperator
bool isOperator(const string& input);
//Function prototype for perforOperation
int performOperation(const string& input, RPN& calculator);
Int main(){
RPN calculator;
string input;
float num;
cout << "RPN Calculator: " << endl;
cout << "Input\n";
while(input != "0")
{
//Terminate program when 0 is entered by user
while(true)
{
// get input
cin >> input;
// check for being numeric value
if(istringstream(input) >> num)
{
//use push function
calculator.push(num);
}
// check for operator
else if(isOperator(input))
{
performOperation(input, calculator);
}
// If user enters 0 on a line followed by a new line, the program exits ????????????
else if(input == "0\n")
{
return -1;
}
}
}
}
bool isOperator(const string& input)
{
static const string operators ="-+*/";
if (input.length() == 1) // right size to be an operator.
{
return operators.find_first_of(input[0]) != string::npos;
// look in the operator string for the first (and only) character in input
}
return false;
}
int performOperation(const string& input, RPN& calculator)
{
//double firstOperand = 0;
//double secondOperand = 0;
//double result;
/*
if( calculator.size() > 2 ) //Error check gives a false error for last input ???
{
cout << "Error: too many operands" << endl;
return 1;
}
//Error chceck for too many operators ////STILL PRINT OUTPUT???
if( calculator.size() < 2 )
{
cout << "Error: too many operators" << endl;
return 1;
}
*/
switch (input[0])
{
case '+': calculator.add();
calculator.display();
break;
case '-': calculator.subtract();
calculator.display();
break;
case '*': calculator.multiply();
calculator.display();
break;
case '/': calculator.divide();
//if (firstOperand / 0)
//{
// cout << "Error: Divide by 0.\n";
//}
calculator.display();
break;
}
/*
if (secondOperand == 0)
{ // moved this test to here because it's the only place it matters.
cout << "Error: Division by 0.\n";
return -1;
}
*/
return 0;
}
This is the sample input and output
Input Output
10 15 + = 25
10 15 - = -5
2.5 3.5 + = 6 (or 6.0)
10 0 / = Error: Division by zero
10 20 * / = Error: Too many operators
12 20 30 / = Error: Too many operands
-10 -30 - = 20
100 10 50 25 / * - -2 / = -40
I got the error division by 0 check to work, It just keeps printing the output in addition to the error...How could I fix this?
int RPN::divide()
{
double op2;
op2 = pop();
if(op2 != 0.0)
{
push(pop() / op2);
}
else
{
cout << "Error: Division by zero.\n";
return -1;
}
}
The problem is that you always leave the result of the calculation on the stack. So when you do the second calculation you aren't starting with an empty stack. Simple fix is to delete this line in stack::display()
push(temp);
Probably should rename stack::display() to stack::display_and_pop() as well.

C++ Stack values not working correctly

I am trying to implement a system that would perform something like say the user enters 4 5 +. It would add the 4 and 5 (9) and push 9 into the stack.
For some reason the values in the stack are huge numbers so I believe it has something to do with a pointer or accessing a wrong field but I'm pulling my hair out trying to find the error. Any help on what I'm doing wrong?
#include "stack.h"
int main()
{
stack Test;
bool stop = false;
float runningtotal = 0;
while (stop == false)
{
char input;
cin >> input;
if (input == '+') {
int value1 = Test.top();
Test.pop();
int value2 = Test.top();
Test.pop();
cout << value1+value2 << endl;
Test.push(value1 + value2);
}
cout << Test.top();
std::getchar();
std::getchar();
}
And the implementation of stack
#include "stack.h"
stack::stack()
{
maxsize = MaxSize;
currentsize = 0;
sptr = new StackElement[maxsize];
}
stack::~stack()
{
delete [] sptr;
}
void stack::push(StackElement data)
{
if (currentsize < maxsize)
{
sptr[currentsize] = data;
currentsize++;
} else {
cout << "Stack is full ;-;";
}
}
void stack::pop()
{
if (currentsize == 0) {
cout << "Empty stack? ;-;";
return;
}
currentsize--;
}
StackElement stack::top()
{
if (currentsize == 0) {
cout << "Empty stack u ninja ;-;";
return NULL;
} else {
return (sptr[currentsize]);
}
}
void stack::push(StackElement data)
{
if (currentsize < maxsize)
{
sptr[currentsize] = data;
currentsize++; //<--- incrementing after so nothing in [currentsize] now
} else {
cout << "Stack is full ;-;";
}
}
StackElement stack::top()
{
if (currentsize == 0) {
cout << "Empty stack u ninja ;-;";
return NULL;
} else {
return (sptr[currentsize]);// should use currentsize-1
// latest filled cell
// since its pushing from top
}
}
Be sure to convert those ascii codes(49 ish) from keyboard to integer type explanations.
input - 48 should do it.

Infix to Postfix calculator, implement sin cos and X&Y variables?

I'm pretty green at C++, and I have to make an infix to postfix calculator that supports sin() and cos(), and it has to be a 2 variable function, something like z=3x*sin(3+4y), I already got the parser from infix to postfix, but I don't know how to implement sin and cos, I've been told that I could set them as operator, like +, -, /, etc. and to set a specific token for them, like "s" for sin() and "c" for cos() but I don't exactly know how, and I don't know either how to implement the variables x & y, I know that this is not something I should be asking, but I'm just tired and desperate.
Here's the code I have. I'm using Ubuntu 11:
#include <iostream>
#include <cmath>
#include <cstdlib>
#include <string>
#define MAX_SIZE 20
using namespace std;
template<class T> class Stack
{
private:
T item[MAX_SIZE];
int top;
public:
Stack()
{
top = -1;
}
void push(T data)
{
if(!this->is_full())
item[++top] = data;
else
{
cout << "Stack Error" << endl;
exit(10);
}
}
T pop()
{
if(!this->is_empty())
{
return item[top--];
}
else
{
cout << "Stack is Empty" << endl;
exit(11);
}
}
int size()
{
return top + 1;
}
bool is_empty()
{
if(top == -1)
return true;
else
return false;
}
bool is_full()
{
if(top == MAX_SIZE - 1)
return true;
else
return false;
}
void display()
{
for(int i = 0; i < this->size(); i++)
{
cout << item[i] << " ";
}
cout << endl;
}
T return_top()
{
return item[top];
}
};
class Convert
{
private:
bool num_flag;
bool two_digit_flag;
public:
Convert();
string return_with_bracket(string infix);
void to_Postfix(string infix,char postfix[]);
bool prcd(char op1, char op2);
int isOperand(char op);
int isOperator(char op);
bool return_flag()
{
return num_flag;
}
};
Convert::Convert()
{
this->num_flag = false;
this->two_digit_flag = false;
}
string Convert::return_with_bracket(string infix)
{
return("(" + infix + ")");
}
bool Convert::prcd(char op1, char op2)
{
if((op1 == '+' || op1 == '-' || op1 == '*' || op1 == '/') && op2 == '(')
return true;
if(op1=='+' && op2=='+')
return true;
if(op1=='-' && op2=='-')
return false;
if(op1=='-' && op2=='+')
return false;
if(op1=='+' && op2=='-')
return false;
if(op1=='/' && op2=='/')
return false;
if(op1=='/' && (op2=='-' || op2=='+'))
return true;
if(op1=='*' && (op2=='+' || op2=='-'))
return true;
if((op1 == '-' || op1 == '+') && (op2 =='*' || op2 == '/'))
return false;
if((op1 == '$' || op1 == '+') && (op2 =='*' || op2 == '/' || op2=='-'))
return true;
if((op1 == '-' || op1 == '+' || op1 =='*' || op1 == '/')&& op2=='^')
return false;
if(op1 == '^' && ( op2 == '+' || op2 =='*' || op2 == '/' || op2=='-'))
return false;
}
int Convert::isOperand(char op)
{
return(op >= '0' && op <= '9');
}
int Convert::isOperator(char op)
{
return(op =='+' || op =='-' || op == '/' || op =='*' || op =='^');
}
void Convert::to_Postfix(string infix, char postfix[])
{
int position, outpos=0;
char c;
int count = 0;
char temp;
char stacktop;
Stack<char> stack;
for(position = 0; (c = infix[position]) != '\0'; position++)
{
if(this->isOperand(c))
{
postfix[outpos++] = c;
this->num_flag = true;
count++;
if(count >= 2)
{
this->two_digit_flag = true;
}
}
else if(this->isOperator(c))
{
count = 0;
if(isOperator(infix[position]) && isOperator(infix[position + 1]))
{
cout << " '\' aMissing argument in between " << infix[position] << " and " << infix[position + 1] << " in column " << position + 1 << endl;
exit(9);
}
if(this->prcd(c, stacktop))
{
stacktop = stack.return_top();
stack.push(c);
stacktop = c;
}
else
{
while(true)
{
temp = stack.pop();
postfix[outpos++] = temp;
stacktop = stack.return_top();
if(prcd(c, stacktop) || stacktop == '(')
break;
}
stack.push(c);
stacktop = stack.return_top();
}
}
else if(c == '(')
{
count = 0;
stack.push(c);
stacktop = stack.return_top();
}
else if(c == ')')
{
count = 0;
while(1)
{
if(stack.size() == 0)
{
cout << "Warning!! Number of ')' is greater than '('" << endl;
exit(2);
}
temp = stack.pop();
if(temp != '(')
{
postfix[outpos++] = temp;
}
else
{
break;
}
}
stacktop = stack.return_top();
}
else
{
cout << "Invalid input";
exit(3);
}
if(infix[position] == ')' && infix[position + 1] == '(')
{
stack.push('*');
stacktop = stack.return_top();
}
}
if(stack.size() != 0)
{
cout << "Warning!!Number of '(' is greater than ')'" << endl;
// exit(6);
}
if(!this->return_flag())
{
cout << "You must Enter Numeric value for calculation" << endl;
cout << "This program cannot perform operations on variables";
exit(5);
}
if(this->two_digit_flag)
{
cout << "Sory! Althoug u may have entered right string" << endl;
cout << "this program is only for single digit operation" << endl;
exit(8);
}
postfix[outpos] = '\0';
}
class Evaluate
{
public:
double eval(char expr[], Convert &);
double oper(int symb, double op1, double op2);
};
double Evaluate::oper(int symb, double op1, double op2)
{
switch(symb)
{
case '+': return (op1 + op2);
case '-': return (op1 - op2);
case '*': return (op1 * op2);
case '/': return (op1 / op2);
case '^': return (pow(op1, op2));
}
}
double Evaluate::eval(char expr[], Convert &convert)
{
int c, position;
char temp1;
int count = 0;
double opnd1, opnd2, value;
Stack<double> stack;
for(position = 0; (c = expr[position]) != '\0'; position++)
{
if(convert.isOperand(c))
{
temp1 = double(c - '0');
stack.push(temp1);
}
else
{
opnd2 = stack.pop();
if(stack.size() == 0)
{
cout << "This program cannot process unary operation";
exit(1);
}
opnd1 = stack.pop();
value = oper(c, opnd1, opnd2);
stack.push(value);
}
}
if(stack.size() >= 2)
{
cout << "Sory! this program cannot calculate this" << endl;
cout << "Enter +, *, /, - or ^ between bracket" << endl;
exit(4);
}
return (stack.pop());
}
int main()
{
Convert convert;
Evaluate evaluate;
string bracketted_infix;
char infix[50], postfix[50];
char choice;
while(1)
{
cout << "Enter string: ";
cin >> infix;
cout << endl;
cout << "Entered String: " << infix << endl;
bracketted_infix = convert.return_with_bracket(infix);
convert.to_Postfix(bracketted_infix, postfix);
cout << "Equivalent Postfix string: " << postfix << endl;
cout << "RESULT: ";
cout << evaluate.eval(postfix, convert);
cout << "\nCalculate another string?(y/n) ";
cin >> choice;
cout << endl;
if(choice == 'n')
break;
}
return 0;
}