c-resources/CPlusPlus20ForProgrammers-master/examples/ch06/fig06_03.cpp

// fig06_03.cpp
// Using range-based for.
#include <iostream>
#include <array>

int main() {
   std::array items{1, 2, 3, 4, 5}; // type inferred as array<int, 5>

   std::array items2{1, 2, 3, 4, 5};
   // display items before modification
   std::cout << "items before modification: ";
   for (const int& item : items) { // item is a reference to a const int
      std::cout <<  item << "<-- items\n"; 
   }                       
   std::cout << "items2 before modification:\n";
   for (const int& item : items) { // item is a reference to a const int
      std::cout <<  item << "<-- items2\n";
   }

 
   // multiply the elements of items by 2
   for (int& item : items) { // item is a reference to an int
      item *= 2;
   }

   for (int item : items2) { // item is a reference to an int
      item *= 2;
   }

   // display items after modification
   std::cout << "\nitems after modification: \n ";
   for (const int& item : items) {
      std::cout <<  item << "<-- items\n";
   }

   // display items after modification
   std::cout << "\nitems2 after modification:\n ";
   for (const int& item : items2) {
      std::cout <<  item << "<-- items2\n";
   }


   // sum elements of items using range-based for with initialization
   std::cout << "\n\ncalculating a running total of items' values:\n";
   for (int runningTotal{0}; const int& item : items) {
      runningTotal += item;
      std::cout << " running total "<<  item << runningTotal<<"\n";
   }
}


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