stack application.cpp

#include <iostream>
using namespace std;

#define stack_size 10
int top = -1;
char stack[stack_size];

void push(char X)
{

    if (top > stack_size - 1)
        cout << "overflow!\n";
    else
    {
        top++;
        stack[top] = X;
    }
}
char pop()
{
    char X = '!';
    if (top < 0)
    {
        cout << "Underflow!\n";
        return X;
    }
    else
    {

        X = stack[top];
        top--;
    }
    return X;
}

int priority(char op)
{

    if (op == '+' || op == '-')
    {
        return 1;
    }
    if (op == '*' || op == '/')
    {
        return 2;
    }
    if (op == '^')
    {
        return 3;
    }
    return 0;
}

char topElement()
{
    return stack[top];
}

int main()
{
    cout<<"Enter Infix: ";
    char infix[30], postfix[30];

    int n = 13, i;
    for (i = 0; i < n; i++)
    {
        cin >> infix[i];
    }
    int k = 0;
    for (i = 0; i < n; i++)
    {

        char t, s = infix[i];
        if (s == '+' || s == '-' || s == '*' || s == '/')
        {

            while (priority(topElement()) >= priority(s))
            {
                t = pop();
                postfix[k++] = t;
            }
            push(s);
        }
        else if (s == '(')
        {
            push('(');
        }
        else if (s == ')')
        {
            while (topElement() != '(')
            {
                //cout<<"top="<<topElement()<<endl;
                t = pop();
                //cout<<"t="<<t<<endl;
                postfix[k++] = t;
            }
            pop();
        }
        else
        {
            postfix[k++] = s;
        }
    }
    char t = pop();
    while (t != '!')
    {
        postfix[k++] = t;
        t = pop();
    }

    for (i = 0; i < k; i++)
    {
        cout << postfix[i];
    }
}