Beautiful C++: 30 Core Guidelines for Writing Clean, Safe, and Fast Code

Chapter 4.1

F.21: To return multiple “out” values, prefer returning a struct or tuple

The shape of a function signature

When we learn about functions, we learn about taking arguments, manipulating these inputs, and returning a value, an output. A function can take as many argu-ments as you like, but it can only return one thing.

This can cause problems. How do you signal an error condition? As discussed elsewhere, this problem remains without satisfactory resolution, but one historically popular approach is to take an error argument and write to that, while returning the result.

This gives us two kinds of function argument: input parameters and output parameters. The input parameters are used in the evaluation of the function, while the output ...