Exploring C++20: The Programmer's Introduction to C++

© Ray Lischner 2020

R. LischnerExploring C++20https://doi.org/10.1007/978-1-4842-5961-0_55

55. Template Constraints

Ray Lischner¹ 

(1)

Ellicott City, MD, USA

 

One drawback to templates is that they are open to misuse, and accidentally using the wrong type as a template argument can confuse a compiler to such a degree that the error messages it issues require an advanced degree in C++ to decipher. Not to worry, though, because a template author can specify constraints on template arguments. This Exploration describes how to write constraints on your templates.

Constraining a Function Template

Consider what would happen if you were to pass a string to the ipower() function (Listing 54-7), or a floating-point value. The function works correctly only for ...