Go back to Richel Bilderbeek's homepage.

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

 

 

 

 

 

(C++) MakeSquare

 

Math code snippet to square all elements in a container (that is: to multiply each element with itself).

 

There are multiple ways to implement MakeSquare:

  1. Using an algorithm (preferred [1][2])
  2. Using a for-loop

 

 

 

 

 

MakeSquare using an algorithm

 

This is the anwer of exercise #9: No for-loops #14.

 

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

template <class T> struct Square : public std::unary_function<T,T>
{
  const T operator()(const T& x) const { return x*x; }
};

void MakeSquare(std::vector<int>& v)
{
  std::transform(v.begin(),v.end(),v.begin(),Square<int>());
}

 

 

 

 

 

MakeSquare using a for-loop

 

Prefer algorithms over loops [1][2].

 

#include <vector>

void MakeSquare(std::vector<int>& v)
{
  const int sz = v.size();
  for (int i=0; i!=sz; ++i)
  {
    v[i]*=v[i];
  }
}

 

 

 

 

 

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