# (C++) Multiply

Multiply is a math code snippet to multiply each element in a std::vector by a certain value.

Multiply can be defined in multiple ways:

1. Multiply using an algorithm and the C++11 STL
2. Using an algorithm and the STL
3. Using an algorithm and Boost
4. Using a for loop

Prefer algorithms over loops [1][2].

## Multiply using an algorithm and the C++11STL

 #include #include void Multiply(std::vector& v, const int x) {   std::for_each(v.begin(),v.end(),     [x](int& i) { i*=x; } ); }

## Multiply using an algorithm and the STL

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

 #include #include #include #include   void Multiply(std::vector& v, const int x) {   std::transform(v.begin(),v.end(),v.begin(),     std::bind2nd(std::multiplies(),x)); }

## Multiply using an algorithm and Boost

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

 #include #include #include #include #include   void Multiply(std::vector& v, const int x) {   std::transform(v.begin(),v.end(),v.begin(),     boost::bind(std::multiplies(),_1,x)); }

## Multiply using a for loop

 #include   void Multiply(std::vector& v, const int x) {   const int sz = v.size();   for (int i=0; i!=sz; ++i)   {     v[i]*=x;   } }

Prefer algorithms over loops [1][2].

## 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'