Why index starts from 0? Why not 1?

Answer 1

Indexes are an offset from the first position. If you are 0 positions away from the start, you are at the first item. Whether or not there is an item there (which you could count) is not related to the offset.

Starting at 1 makes it easier to confuse 'count of items' with 'offset to item'.

Answer 2

First answer, "historical reasons":
https://stackoverflow.com/a/22547440
"Translation: They don't want to write all new plot, print, etc. routines."

Next answer down: Because people using Matlab aren't necessarily programmers... 0 vs 1 is a source of bugs here. (Some programming languages tried to be more approachable in the same way, opinions vary)

In my opinion, programmers have the additional responsibility to go beyond 'catering to the people'. Unfortunately this means tracking who went with popular (the politically correct: 1) vs. accurate (this is how distance works: 0).

Answer 3

because index is the distance from first character.

Answer 4

But the index starts from 1 in MATLAB