从本书介绍到使用Python进行计算和编程，如何理解关于范围的这句话

Question

I am self learning Python via the book Introduction to Computation and Programming Using Python and I'm stuck on this sentence in the book about range:

If step is positive, the last element is the largest integer start + i*step less than stop.

I think I understand how range works: range(A, B, z) will start at A and try to "reach" B with a step size of z, and it B-1 will be the largest result if the step is 1. But I don't understand the sentence above by Prof. Guttag.

The last element will no doubt be the largest integer will be the largest if the step is positive. But wouldn't the different between the last element and stop be (Stop - (Start + i*step))?

Why did he say that it will be start + i*step less than stop. ?

Answer 1

You are understanding it correctly. He doesn't mean that this is the quantity by which it is smaller than stop . He means that

• it is the largest integer
• that has the form start + i*step
• and is less than (smaller than) stop