The for-each algorithm

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Lecture 5 - Page 34 : 39

Notes about C++
Templates and The Standard Library

The for-each algorithm

In C++ for-each is an algorithm, not a control structure like foreach in C#

C++ 2011 has introduced a 'range based for loop' similar to foreach in C#

// The C++ Programming Language, 3ed, page 524.
// Possible definition of the for_each function template. 
template <class In, class Op> Op for_each(In first, In last, Op f){
  while (first != last) f(*first++);
  return f;
}

A possible implementation of the for-each algorithm.

Implementation and sample use of for-each on an C-style array.

Implementation and sample use of for-each on a list of integers.

A Stroustrup advice:
- "In general, before using for_each(), consider if there is a more specialized algorithm that would do more for you"
  - Such as find() or accumulate()

Observation about the return-value of for_each
- The function f of type Op is returned.
  - Later we will see an example where this is convenient