2.5.1 Beginning and End of Sequence

What was the problem

All containers from the STL have a begin() and end() member function to get an iterator on the first element in the sequence or, respectively, just after the last element. Unfortunately, there is no such function for the most basic sequences, i.e. C-like arrays, so code like that was sure to fail before C++11:

template<typename Sequence, typename T> 
void replace_existing 
(Sequence& s, const T& old_value, const T& new_value) 
{ 
  *std::find(s.begin(), s.end(), old_value) = new_value; 
} 
 
void foo() 
{ 
  int a[] = { 1, 4, 3 }; 
  replace_existing(a, 4, 2); 
}

How the Problem is Solved

Fortunately, C++11 introduces the std::begin() and std::end() free functions which accepts a C-like array⁵. Now, this code will work in all cases:

template<typename Sequence, typename T> 
void replace_existing 
(Sequence& s, const T& old_value, const T& new_value) 
{ 
  *std::find(std::begin(s), std::end(s), old_value) = new_value; 
} 
 
void foo() 
{ 
  int a[] = { 1, 4, 3 }; 
  replace_existing(a, 4, 2); 
}