Using streams on fixed-size external buffers

The <strstream> header has been part of the standard I/O library from its beginning. It contains classes that provide stream operations on sequences of characters stored in an array. However, this header was deprecated a long time ago, in C++98, although it’s still available because a replacement wasn’t available. The C++20 standard has introduced the std::span class, which is a non-owning view of a sequence of objects. In C++23, a new header, <spanstream>, has been added as a replacement for <strstream>. This contains classes that provide stream operations on externally provided memory buffers. In this recipe, we’ll learn how to parse or write text using the I/O span streams.

How to do it…

Use the new C++23 span streams as follows:

• To parse text from an external array, use std::ispanstream:

  char text[] = "1 1 2 3 5 8";
  std::ispanstream is{ std::span<char...