Conventions
To use the algorithms, you have to keep a few rules in your head.
The algorithms are defined in various headers.
<algorithm>- Contains the general algorithms.
<numeric>- Contains the numeric algorithms.
Many of the algorithms have the name suffix _if and _copy.
_if- The algorithm can be parametrized by a predicate.
_copy- The algorithm copies its elements in another range.
Algorithms like auto num= std::count(InpIt first, InpIt last, const T& val) return the number of elements that are equal to val. num is of type iterator_traits<InpIt>::difference_type. You have the guarantee that num is sufficient to hold the result. Because of the automatic return type deduction with auto, the compiler will give you the right types.
