Using std::string_view instead of constant string references

When working with strings, temporary objects are created all the time, even if you might not be really aware of it. Many times, these temporary objects are irrelevant and only serve the purpose of copying data from one place to another (for example, from a function to its caller). This represents a performance issue because they require memory allocation and data copying, which should be avoided. For this purpose, the C++17 standard provides a new string class template called std::basic_string_view, which represents a non-owning constant reference to a string (that is, a sequence of characters). In this recipe, you will learn when and how you should use this class.

Getting ready

The string_view class is available in the namespace std in the string_view header.

How to do it...

You should use std::string_view to pass a parameter to a function (or return a value from a function), instead of std::string const...