C-Plus-Plus-Projects/suffix 2 prefix at main · kokonior/C-Plus-Plus-Projects · GitHub

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#include <iostream>
#include <stack>
using namespace std;

bool Cprec(char c){
  if(c == '+' || c == '-' || c == '*' || c == '/'){
    return true;
  }
  else{
    return false;
  }
}

int prec(char c){
  if(c == '*' || c == '/')
  return 2;
  else if(c == '+' || c == '-')
  return 1;
  else
  return -1;
}


string Infix2Suffix(stack<char> s,string infix) {
  	string postfix;
    for(int i=0;i<infix.length();i++){
      if((infix[i] >= 'a' && infix [i] <= 'z') ||
      (infix[i] >= 'A' && infix [i] <= 'Z' ) ||
      (infix[i] >= '0' && infix [i] <= '9')){
        postfix += infix[i];
      }
      else if(infix[i] == '('){
        s.push(infix[i]);
      }
      else if(infix[i] == ')'){
        while((s.top()!='(') && (!s.empty())){
          char temp = s.top();
          postfix += temp;
          s.pop();
        }
      }
      else if(Cprec(infix[i])){
        if(s.empty()){
          s.push(infix[i]);
        }
        else{
          if(prec(infix[i])>prec(s.top())){
            s.push(infix[i]);
          }
          else{
            while((!s.empty()) && (prec(infix[i])<=prec(s.top()))){
              char temp = s.top();
              postfix += temp;
              s.pop();
            }
            s.push(infix[i]);
          }
        }
      }
    }
    while(!s.empty()){
      postfix += s.top();
      s.pop();
    }


    return postfix;
}


int main() {
  char ans[2];
  string exp, postfix;
  do{
    cout << "Put the infix expression: " << endl;
    getline (cin,exp);
    stack<char> stack;
    postfix = Infix2Suffix(stack, exp);
    cout << "The postfix expression: " << postfix << endl;
    cout << "Take another data? (Y/N) ";
    cin >> ans;
    cin.ignore();
  }while(ans[0] == 'Y' || ans[0] == 'y');
  return 0;
}