#insclude<iostream>
#include<stack>
#include<string>
using namespace std;
string InfixToPostfix(string
expression);
int HasHigherPrecedence(char
operator1, char operator2);
bool IsOperator(char C);
bool IsOperand(char C);
int main()
{
string expression;
cout<<"Enter Infix Expression \n";
getline(cin,expression);
string postfix = InfixToPostfix(expression);
cout<<"Output =
"<<postfix<<"\n";
}
string InfixToPostfix(string
expression)
{
stack<char> S;
string postfix = "";
for(int i = 0;i< expression.length();i++) {
if(expression[i] == ' ' || expression[i] ==
',') continue;
else if(IsOperator(expression[i]))
{
while(!S.empty() &&
S.top() != '(' && HasHigherPrecedence(S.top(),expression[i]))
{
postfix+= S.top();
S.pop();
}
S.push(expression[i]);
}
else if(IsOperand(expression[i]))
{
postfix +=expression[i];
}
else if (expression[i] == '(')
{
S.push(expression[i]);
}
else if(expression[i] == ')')
{
while(!S.empty() &&
S.top() != '(') {
postfix += S.top();
S.pop();
}
S.pop();
}
}
while(!S.empty()) {
postfix += S.top();
S.pop();
}
return postfix;
}
bool IsOperand(char C)
{
if(C >= '0' && C <= '9') return true;
if(C >= 'a' && C <= 'z') return true;
if(C >= 'A' && C <= 'Z') return true;
return false;
}
bool IsOperator(char C)
{
if(C == '+' || C == '-' || C == '*' || C == '/' || C==
'$')
return true;
return false;
}
int IsRightAssociative(char
op)
{
if(op == '$') return true;
return false;
}
int GetOperatorWeight(char op)
{
int weight = -1;
switch(op)
{
case '+':
case '-':
weight = 1;
case '*':
case '/':
weight = 2;
case '$':
weight = 3;
}
return weight;
}
int HasHigherPrecedence(char
op1, char op2)
{
int op1Weight = GetOperatorWeight(op1);
int op2Weight = GetOperatorWeight(op2);
if(op1Weight == op2Weight)
{
if(IsRightAssociative(op1)) return false;
else return true;
}
return op1Weight > op2Weight ? true: false;
}
OUTPUT
OUTPUT
