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Infix to Postfix Please Help!!

hockey34 (15)
My infix is A * B + C * D * E + F and the postfix that is outputting is A B C D E F + * * + * which is incorrect. Please help me get correct output. Here is my code:
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  #include <iostream>
#include <string>
using std::cout;
using std::cin;
using std::endl;
using std::string;

struct node{
    char value;
    struct node *link;
};

node *top;

class stack{
private:
    int counter;
public:
    node *pushInto(node*, char);
    node *popOut(node*);
    void traverseStack(node*);
    int isStackEmpty();
    stack()
    {
        top = nullptr;
        counter = 0;
    }
};

node *stack::pushInto(node *top, char a)
{
    node *temp;
    temp = new (struct node);
    temp -> value = a;
    temp -> link = top;
    top = temp;
    counter++;
    return top;
}

node *stack::popOut(node *top)
{
    node *temp;
    char item;
    if (top == nullptr)
    {
        cout << "Stack is empty";
    }
    else
    {
        temp = top;
        item = temp -> value;
        cout << item;
        top = top -> link;
        delete temp;
        counter--;
    }
    return top;
}

void stack::traverseStack(node *top)
{
    node *temp;
    temp = top;
    if (top == nullptr)
    {
        cout << "Stack is empty.";
    }
    else
    {
        while (temp != nullptr)
        {
            cout << temp -> value << endl;
            temp = temp -> link;
        }
    }
}

int stack::isStackEmpty()
{
    if (top == nullptr)
        return 0;
    return -1;
}

class infixToPostfix:public stack{
public:
    bool isOperand(char);
    bool isOperator(char);
    int weightOfOperator(char);
    char precedence(char, char);
    void output(char[]);
};

bool infixToPostfix::isOperand(char a)
{
    if (a >= 'A' && a <= 'Z')
        return true;
    return false;
}

bool infixToPostfix::isOperator(char a)
{
    if (a == '*' || a == '/' || a == '+' || a == '-')
        return true;
    return false;
}

int infixToPostfix::weightOfOperator(char a)
{
    int weight;
    
    if (a == '*' || a == '/')
        weight = 2;
    else if (a == '+' || a == '-')
        weight = 1;
    else
        weight = -1;
    return weight;
}

char infixToPostfix::precedence(char a, char b)
{
    if (weightOfOperator(a) > weightOfOperator(b))
    {
        return a;
    }
    return b;
}

void infixToPostfix::output(char a[])
{
    const int length = 11;
//    const int numberOperators = 5;
    char output[length];
    for (int i = 0; i < length; i++)
    {
        if (isOperand(a[i]))
        {
            output[i] = a[i];
        }
        else
        {
            top = pushInto(top, a[i]);
        }
        cout << output[i];
    }

    for (int i = 1; i < length; i+=2)
    {
        if (precedence(a[i], a[i + 1]))
        {
            top = popOut(top);
        }
    }
}

int main()
{
    infixToPostfix result;
    const int length = 11;
    char infix1[length] = {'A', '*', 'B', '+', 'C', '*', 'D', '*', 'E', '+', 'F'};  //Initalize and declare first infix pattern
  //  char infix2[length] = {'A', '+', 'B', '*', 'C', '+', 'D', '+', 'E', '*', 'F'};
    
    result.output(infix1);
    cout << "\n";
//    result.output(infix2);
    
    return 0;
}
hockey34 (15)
bump, anyone???
Enoizat (1342)
Hi, hockey34.
There’s at least an error in logic.
You should not pop out all the operators after you have pushed all them into the stack. It should be more a ‘push into, get out of’ game, so to say.

For example, in your string "A * B + C * D * E + F" , when you get into the first ‘+’, the ‘*’ into the stack should be rescued, because it has got a higher precedence.

I’ve changed your code to make the ‘output’ routine describe every single step, and I think it makes the things clearer:
MyStack.h
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#ifndef MYSTACK_H
#define MYSTACK_H

#include <iostream>

struct Node{
    char value;
    Node *link;
};

class MyStack
{
public:
    MyStack() = default;
    Node *pushNodeInto(Node*, char);
    Node *popNodeOut(Node*);
    void traverseStack(Node*);
    bool isEmpty();

protected:
    Node *top {nullptr};
    int counter {0};
};

#endif // MYSTACK_H


MyStack.cpp
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#include "MyStack.h"

Node* MyStack::pushNodeInto(Node *top, char tobepushed)
{
    Node *temp = new (Node);
    temp->value = tobepushed;
    temp->link = top;
    top = temp;
    counter++;

    return top;
}

Node* MyStack::popNodeOut(Node *top)
{
    Node *temp;
    char item;
    if (top == nullptr)
    {
        std::cout << "Stack is empty\n";
    }
    else
    {
        temp = top;
        item = temp->value;
        std::cout << item;
        top = top->link;
        delete temp;
        counter--;
    }

    return top;
}

void MyStack::traverseStack(Node *top)
{
    Node *temp;
    temp = top;
    if (top == nullptr)
    {
        std::cout << "Stack is empty.\n";
    }
    else
    {
        while (temp != nullptr)
        {
            std::cout << temp->value << std::endl;
            temp = temp->link;
        }
    }
}

bool MyStack::isEmpty()
{
    if (top == nullptr)
        return true;

    return false;
}


InfixToPostfix.h
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#ifndef INFIXTOPOSTFIX_H
#define INFIXTOPOSTFIX_H

#include <string>
#include "MyStack.h"

class InfixToPostfix : public MyStack
{
public:
    InfixToPostfix();
    bool isOperand(char);
    bool isOperator(char);
    int weightOfOperator(char);
    char precedence(char, char);
    void print(std::string);
};

#endif // INFIXTOPOSTFIX_H


InfixToPostfix.cpp
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#include <iostream>
#include "InfixToPostfix.h"

InfixToPostfix::InfixToPostfix()
{}

bool InfixToPostfix::isOperand(char tobetested)
{
    if ('A' <= tobetested && tobetested <= 'Z')
        return true;

    return false;
}

bool InfixToPostfix::isOperator(char tobetested)
{
    switch (tobetested) {
    case '*':
    case '/':
    case '+':
    case '-':
        return true;
        break;
    default:
        break;
    }

    return false;
}

int InfixToPostfix::weightOfOperator(char oper)
{
    switch (oper) {
    case '*':
    case '/':
        return 2;
        break;
    case '+':
    case '-':
        return 1;
        break;
    default:
        break;
    }

    return -1; // ?? error code?
}

char InfixToPostfix::precedence(char a, char b)
{
    if (weightOfOperator(a) > weightOfOperator(b))
    {
        return a;
    }

    return b;
}

void InfixToPostfix::print(std::string str)
{
    std::cout << "\nPassed infix: " << str << '\n';
    std::string output;
    for (size_t i = 0; i < str.length(); i++)
    {
        std::cout << "str.at(i) = \'" << str.at(i) << "\' --> ";
        if (isOperand(str.at(i)) || str.at(i) == ' ')
        {
            output += str.at(i);
            std::cout << "adding \'" << str.at(i)
                      << "\' to unused \"output\"\n";
        }
        else
        {
            top = pushNodeInto(top, str.at(i));
            std::cout << "pushing \'" << str.at(i)
                      << "\' into MyStack\n";
        }
    }

    for (size_t i = 1; i < str.length(); i+=2)
    {
        if (precedence(str.at(i), str.at(i+1)))
        {
            top = popNodeOut(top);
            std::cout << "Popping \'" << top->value
                      << "\' out of MyStack\n";
        }
    }
    std::cout << '\n';
}


main.cpp:
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#include <iostream>
#include <string>
#include "InfixToPostfix.h"

int main()
{
    InfixToPostfix result;

      //Initalize and declare first infix pattern
    std::string infix1 = "A * B + C * D * E + F";
    result.print(infix1);

    return 0;
}


Output:

Passed infix: A * B + C * D * E + F
str.at(i) = 'A' --> adding 'A' to unused "output"
str.at(i) = ' ' --> adding ' ' to unused "output"
str.at(i) = '*' --> pushing '*' into MyStack
str.at(i) = ' ' --> adding ' ' to unused "output"
str.at(i) = 'B' --> adding 'B' to unused "output"
str.at(i) = ' ' --> adding ' ' to unused "output"
str.at(i) = '+' --> pushing '+' into MyStack
str.at(i) = ' ' --> adding ' ' to unused "output"
str.at(i) = 'C' --> adding 'C' to unused "output"
str.at(i) = ' ' --> adding ' ' to unused "output"
str.at(i) = '*' --> pushing '*' into MyStack
str.at(i) = ' ' --> adding ' ' to unused "output"
str.at(i) = 'D' --> adding 'D' to unused "output"
str.at(i) = ' ' --> adding ' ' to unused "output"
str.at(i) = '*' --> pushing '*' into MyStack
str.at(i) = ' ' --> adding ' ' to unused "output"
str.at(i) = 'E' --> adding 'E' to unused "output"
str.at(i) = ' ' --> adding ' ' to unused "output"
str.at(i) = '+' --> pushing '+' into MyStack
str.at(i) = ' ' --> adding ' ' to unused "output"
str.at(i) = 'F' --> adding 'F' to unused "output"
+Popping '*' out of MyStack
*Popping '*' out of MyStack
*Popping '+' out of MyStack
+Popping '*' out of MyStack

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