Int is the definition of integer variable in C language. Int i is to define an integer variable I, which is an integer in the next use. For example, i= 1 or other integer. If you set i= 1. 1, the system will report an error or automatically change it to i= 1. A[8] is an array, and int a[8] defines an array that can store up to 8 integers. The array subscripts from 0 to 7, although it may not be complete, but it can store up to 8 integers. For example, as shown below: