C++20 STL Cookbook

Chapter 6: STL Algorithms

Much of the power of the STL is in the standardization of container interfaces. If a container has a particular capability, there's a good chance that the interface for that capability is standardized across container types. This standardization makes possible a library of algorithms that operate seamlessly across containers and sequences sharing a common interface.

For example, if we want to sum all the elements in a vector of int, we could use a loop:

vector<int> x { 1, 2, 3, 4, 5 };

long sum{};

for( int i : x ) sum += i;                     // sum is 15

Or we could use an algorithm:

vector<int> x { 1, 2, 3, 4, 5 };

auto sum = accumulate(x.begin(), x.end(), 0);  // sum is 15

This same syntax works with other containers: ...