foreach.h

This file defines the foreach keyword, which implements a substitute for the range-based for loop from C++11. All iterable classes in the Stanford libraries import this file, so clients don't ordinarily need to do so explicitly. This version of foreach also supports C++ strings and arrays.
Statement
foreach(type var in collection) The foreach statement steps through the elements in a collection.

Statement detail

foreach (type var in collection) { ... }
The foreach statement steps through the elements in a collection. It works correctly with the collection classes in both the Standard Template Library and the Stanford C++ libraries, but can also be used with C++ strings and statically initialized arrays.

The following code, for example, prints every element in the string vector lines: 

   foreach (string str in lines) {
      cout << str << endl;
   }
Similarly, the following function calculates the sum of the character codes in a string: 
   int sumCharacterCodes(string str) {
      int sum = 0;
      foreach (char ch in str) sum += ch;
      return sum;
   }
As a simplification when iterating over maps, the foreach macro iterates through the keys rather than the key/value pairs.