Exercise 2.7. Write a function to compute the product 1 n, for positive n. Write a main function to call it, and illustrate various interesting memory configurations during its execution. Use the protection and naming conventions of Exercise 2.6. (This is in C)

The function sum checks its input and invokes sum if the input is well formed: 1/* Interface for computing the sum 2 1 + 2 + 3 + 31 * Returns -1 if n 0 at this point, so we can safely 1 // call the helper function. 12 _sum(n); 13 -4 // success 51 return 0; -63 Although the check that n > O is simple, this pattern of separating the main computation from the external interface is common in situations in which the input check is more complex. Finally, main tests sum with both well formed and malformed input. It uses the output function printf, which is discussed in depth in Chapter 5, to print the sum to the console: 1 int main() { 21 // test the sum function int S, err; err - sum (5, &s); assert (err -- 0); // print the result to the console printf("%d ", s); // test bad input err - sum(-3, ks); assert (err - 0); return 0; 2) Compiling and running the program yields the expected output of 15: $ gcc -Wall -Wextra -o sum sum.c $ ./sum 15 3 4 5 6 71 81 91 201 Exercise 2.7. Write a function to compute the product 1 x ... x n, for pos- itive n. Write a main function to call it, and illustrate various interesting memory configurations during its execution. Use the protection and naming conventions of Exercise 2.6