Go back to Richel Bilderbeek's homepage.

Go back to Richel Bilderbeek's C++ page.

 

 

 

 

 

(C++) Add

 

Add is a math code snippet to add a certain same value to each element in a std::vector.

 

There are multiple ways to perform Add:

  1. C++0xSTL The C++0x algorithm way on a std::vector<int>
  2. C++98STL The C++98 algorithm way on a std::vector<int>
  3. C++98 The for-loop way on a std::vector<int>

 

 

 

 

 

 

C++0xSTL The C++0x algorithm way on a std::vector<int>

 

Prefer algorithms over loops [1][2]

 

#include <algorithm>
#include <vector>

//From http://www.richelbilderbeek.nl/CppAdd.htm
const std::vector<int> AddCpp0x(const std::vector<int>& v, const int x)
{
  std::vector<int> w(v);
  std::for_each(w.begin(),w.end(),[x](int&i) { i+=x; } );
  return w;
}

 

 

 

 

 

C++98STL The C++98 algorithm way on a std::vector<int>

 

Prefer algorithms over loops [1][2]

 

#include <algorithm>
#include <functional>
#include <numeric>
#include <vector>

//From http://www.richelbilderbeek.nl/CppAdd.htm
const std::vector<int> Add(const std::vector<int>& v, const int x)
{
  std::vector<int> v_new;
  std::transform(v.begin(),v.end(),std::back_inserter(v_new),
    std::bind2nd(std::plus<int>(),x));
  return v_new;
}

 

This is the answer of Exercise #9: No for-loops.

 

 

 

 

 

C++98 The for-loop way on a std::vector<int>

 

Prefer algorithms over loops [1][2]

 

#include <vector>

const std::vector<int> Add(const std::vector<int>& v, const int x)
{
  std::vector<int> v_new(v); //Copy original vector
  const int sz = v.size();
  for (int i=0; i!=sz; ++i)
  {
    v_new[i]+=x;
  }
  return v_new;
}

 

 

 

 

 

References

 

  1. Bjarne Stroustrup. The C++ Programming Language (3rd edition). ISBN: 0-201-88954-4. Chapter 18.12.1 : 'Prefer algorithms over loops'
  2. Herb Sutter and Andrei Alexandrescu. C++ coding standards: 101 rules, guidelines, and best practices. ISBN: 0-32-111358-6. Chapter 84: 'Prefer algorithm calls to handwritten loops.'

 

 

 

 

 

Go back to Richel Bilderbeek's C++ page.

Go back to Richel Bilderbeek's homepage.

 

Valid XHTML 1.0 Strict