What is half open range and off the end value

Question

What do these terminologies mean in C++?

1. off the end value

2. half open range - [begin, off_the_end)

Answer 1

These aren't C++ specific terms, they are general maths terms.

[] and () denote whether the range is inclusive/exclusive of the endpoint:

• [ includes the endpoint
• ( excludes the endpoint
• [] = 'Closed', includes both endpoints
• () = 'Open', excludes both endpoints
• [) and (] are both 'half-open', and include only one endpoint

Most C++ for-loops cover a half-open range (you include the first element: e.g for int i=0;, but exclude the final element: i < foo, not i ≤ foo)