If Step is not specified, the loop counter is incremented by 1. In this case, End must be greater than Start. If you want to decrease Counter, End must be less than Start and Step must be assigned a negative value.
设置循环计数器递增或递减的步长值。如果不指定 Step，则循环计数器的增量为 1。在这种情况下，End 必须大于 Start。如果要递减计数器，则 End 必须小于 Start，并且必须将 Step 指定为负值。