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  1. #include <iostream>
  2. #include <sstream>
  3. #include <stack>
  4. #include <cctype>
  5.  
  6. using namespace std;
  7.  
  8. int main () {
  9.   istringstream is ("4.5 7.89  + 45.2  2*");
  10.   stack<double> operands;
  11.   double acc = 0;
  12.  
  13.   while (!is.eof()) {
  14.     double operand;
  15.     char   oper;
  16.  
  17.     if (is >> oper && !isdigit(oper)) {
  18.         switch (oper) {
  19.           case '+': {
  20.             while (!operands.empty()) {
  21.               acc += operands.top(); 
  22.               operands.pop();
  23.             }
  24.           } break;
  25.           case '-': {
  26.             while (!operands.empty()) {
  27.               acc -= operands.top();
  28.               operands.pop();
  29.             }
  30.           } break;
  31.           case '*': {
  32.             if (acc == 0 && !operands.empty()) {
  33.               acc = operands.top();
  34.               operands.pop();
  35.             }
  36.             while (!operands.empty()) {
  37.               acc *= operands.top();
  38.               operands.pop();
  39.             }
  40.           } break;
  41.            // etc
  42.         }
  43.       } else {
  44.         is.unget();
  45.         is >> operand;
  46.         operands.push (operand);
  47.       }
  48.     }
  49.  
  50.   cout << "Result: " << acc << endl;
  51. }
  52.  
  53.  
Success #stdin #stdout 0.02s 2864KB
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Standard input is empty
stdout
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Result: 1120.06
https://ideone.com/TykfX
language:
C++ (gcc 8.3)
created:
12 years ago
visibility:
secret

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