Question

Why we use zero always at the start of any array in C++?

Answer 1

We start at an index of 0, in a lot, if not all, of today's coding languages.

The use of index is to describe the offset from the beginning. While we describe the 1st value in an array as element 1, we obtain it using the index of 0 since it's right at the beginning.

This link may give you a better understanding: https://developerinsider.co/why-does-the-indexing-of-array-start-with-zero-in-c/

Answer 2

Just in case if you meant zeroing an array in C/C++

char myBuffer[20] = { 0 };

This is to set the memory occupied by myBuffer all to 0 (or '\0', or terminating zero) to remove any previous content from that memory address and make sure we know what's there. A terminating zero indicates the end of a string, so the above code effectively sets myBuffer to be empty.

If you meant why do we start indexing an array at 0 index (instead of 1), that is, why the first element is at position 0, not 1, please see LiOS's answer.