int x[5]；

This means that you applied for an array (it is the same as a row of seats, that is, five seats, the first seat is called x[0], the second seat is called X [1] ... and the last seat is called x[4]. Note that there is no x[5]. This is the definition, starting from 0, there is no reason! )

So there are numbers in [], indicating how many "seats" there are

Application method: x [0] = 3; It is the' 0' seat that makes a' person' with the number 3, and the number' 3' will be used when x[0] is used in the future. Change the method and re-assign x [0] = 4; So ... this place ranks fourth.

Note that because it starts with int, you can only fill in "integer" here!

If you don't understand, you can continue to ask, hoping to help you ~