The increment operator
(Display Listing 1.)
The index value is incremented (increased) by a value of one at the end of the code in the body of the loop using an increment operator (++).
This is an operator that I haven't previously explained.
The increment operator is a unary operator, meaning that it has only one operand.
When the increment operator follows the name of a variable (postfix configuration), a value of 1 is added to the current value stored in the variable.