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// C++ code to convert infix expression to postfix
#include <bits/stdc++.h>
using namespace std;
// Function to return precedence of operators
int prec(char c)
{
if (c == '^')
return 3;
else if (c == '/' || c == '*')
return 2;
else if (c == '+' || c == '-')
return 1;
else
return -1;
}
// The main function to convert infix expression
// to postfix expression
void infixToPostfix(string s)
{
stack<char> st;
string result;
for (int i = 0; i < s.length(); i++) {
char c = s[i];
// If the scanned character is
// an operand, add it to output string.
if ((c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z')
|| (c >= '0' && c <= '9'))
result += c;
// If the scanned character is an
// ‘(‘, push it to the stack.
else if (c == '(')
st.push('(');
// If the scanned character is an ‘)’,
// pop and add to output string from the stack
// until an ‘(‘ is encountered.
else if (c == ')') {
while (st.top() != '(') {
result += st.top();
st.pop();
}
st.pop();
}
// If an operator is scanned
else {
while (!st.empty()
&& prec(s[i]) <= prec(st.top())) {
result += st.top();
st.pop();
}
st.push(c);
}
}
// Pop all the remaining elements from the stack
while (!st.empty()) {
result += st.top();
st.pop();
}
cout << result << endl;
}
// Driver code
int main()
{
string exp = "a+b*(c^d-e)^(f+g*h)-i";
// Function call
infixToPostfix(exp);
return 0;
}