Modern C++ Programming Cookbook

Getting ready

Map is a higher-order function that applies a function to the elements of a range and returns a new range in the same order.

Fold is a higher-order function that applies a combining function to the elements of the range producing a single result. Since the order of the processing can be important, there are usually two versions of this function--foldleft, that processes elements from left to right, and foldright that combines the elements from right to left.

Most descriptions of the function map indicate that it is applied to a list, but this is a general term that can indicate different sequential types, such as list, vector, and array, and also dictionaries (that is, maps), queues, and so on. For this reason, I prefer to use ...