In the first statement, it deletes the variable a and if a is an array, so it deletes the first element of the array or it corrupts the heap pool. In the second statement, it deletes the whole array a[].
In the first statement, it deletes the variable a and if a is an array, so it deletes the first element of the array or it corrupts the heap pool. In the second statement, it deletes the whole array a[].