Why does the indexing start with zero in 'C'?

Question

Why does the indexing in an array start with zero in C and not with 1?

Answer 1

Because 0-based index allows...

array[index]

...to be implemented as...

*(array + index)

If index were 1-based, compiler would need to generate: *(array + index - 1), and this "-1" would hurt the performance.