Infix to Postfix c++/c plus plus

infixToPostFix.cpp

#include<iostream>
#include<stack>//import Stack STL
#include<string>//import String STL
#include<conio.h>
using namespace std;

string infixToPostfix(string expr); //Function declaration
int precendence(char arg);
bool isoperand(char arg);
bool isoperator(char arg);
int operatorweight(char arg);
bool highprecendence(char a, char b);

int main()
{
    string exp;//Variable to get input expression
    cout<<"Enter the infix expression:";
    getline(cin,exp);
    cout<<"Output Postfix Expression:"<<infixToPostfix(exp);
    getch();
}

string infixToPostfix(string expr)//Function to perform all conversion operation
{

    stack<char> stk;//Declaring a stack for conversion purpose
    string postfix = "";//Initialize the output string as empty;
    for(int i = 0;i < expr.length(); i++)//Scan the infix string one by one
        if(expr[i] == '(')
        {
            stk.push(expr[i]);
        }
        else if(expr[i] == ')')
        {
            while(stk.top() != '(')
            {
                postfix = postfix + stk.top();
                stk.pop();
            }
            stk.pop();
        }
        else if(isoperand(expr[i]))
        {
            postfix += expr[i];
        }
        else if(isoperator(expr[i]))
        {
            while(!stk.empty()&& !highprecendence(expr[i],stk.top()))
            {
                postfix+= stk.top();
                stk.pop();
            }
            stk.push(expr[i]);
        }
    while(!stk.empty())
    {
        postfix+= stk.top();
        stk.pop();
    }
    return postfix;
}

bool highprecendence(char a, char b)//Check for operator precendence
{
    int weighta = operatorweight(a);
    int weightb = operatorweight(b);
    if(weighta >= weightb) return 1;
    return 0;
}

bool isoperator(char arg)//Check weather the character is operator
{
    if(arg == '*' || arg == '/' || arg == '+' || arg == '-') return(1);
    else return(0);
}
bool isoperand(char arg)//Check weather the character is operand
{
    if(arg >= '0' && arg <= '9') return 1;
    if(arg >= 'a' && arg <= 'z') return 1;
    if(arg >= 'A' && arg <= 'Z') return 1;
    return 0;
}

int operatorweight(char arg)//Add weight to the operator
{
    int weight = 0;
    switch(arg)
    {
    case '*':
    case '/':
        weight = 2;
        break;
    case '+':
    case '-':
        weight = 1;
        break;
    }
    return(weight);
}