How to Quickly Initialize a std::vector from a C-Style Array?

Assigning a std::vector from a C-Style Array

In various scenarios, it becomes necessary to assign a std::vector using a C-style array. Consider the following class with a vector that needs to be initialized using data passed as a C-style array:

class Foo {
  std::vector<double> w_;
public:
  void set_data(double* w, int len){
   // how to cheaply initialize the std::vector?
}
};

Instead of resizing the vector and iterating over the elements or using std::copy(), a more efficient approach exists. Utilizing the fact that pointers can be treated as iterators, the vector can be quickly assigned using:

w_.assign(w, w + len);

This syntax assigns the range from the pointer w to w len, effectively initializing the vector with the values from the C-style array.

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