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infix_to_postfix.cpp
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infix_to_postfix.cpp
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#include<iostream>
#include<stack>
using namespace std;
// infix to postfix evaluation
int precedence(char ch){
if(ch=='^'){
return 3;
}
else if(ch=='*' || ch=='/'){
return 2;
}
else if(ch=='+' || ch=='-'){
return 1;
}
else {
return -1;
}
}
string Infix_To_Postfix(string s){
stack<char> st;
string result;
for(int i =0;i<s.length();i++){
if((s[i]>='a' && s[i]<='z') || (s[i]>='A' && s[i]<='Z')){
result+=s[i];
}
else if(s[i]=='('){
st.push(s[i]);
}
else if(s[i]==')'){
while(!st.empty() && st.top()!='('){
result+=st.top();
st.pop();
}
if(!st.empty()){
st.pop();
}
}
else{
while(!st.empty() && precedence(st.top()) > precedence(s[i])){
result+=st.top();
st.pop();
}
st.push(s[i]);
}
}
while(!st.empty()){
result+=st.top();
st.pop();
}
return result;
}
int main()
{
string exp;
cout << "Enter the infix expression : " << endl;
cin >> exp;
cout << Infix_To_Postfix(exp);
// cout << Infix_To_Postfix("(a-b/c)*(a/k-l)") << endl;
}