1 files changed, 2 insertions, 0 deletions
diff --git a/ratio.c b/ratio.c
index 6d0b59d..f8bfeb0 100644
--- a/ratio.c
+++ b/ratio.c
@@ -9,6 +9,7 @@ typedef unsigned long long num;
 
 typedef struct {bool s; num n; num d;} rational;
 
+/*safe_sum and safe_product abort if computations would exceed maximal value allowd for unsigned long long and overflow.*/
 num safe_sum(num n1, num n2){
 	if(n2 > ULLONG_MAX-n1){
 		printf("Sum overflow: Adding %llu and %llu\n",n1,n2);
@@ -107,6 +108,7 @@ rational product(rational r1, rational r2){
 	rational r;
 	rational s1 = {r1.s, r1.n, r2.d};
 	rational s2 = {r2.s, r2.n, r1.d};
+	/*Cancel as early as possible to avoid exceeding maximal value.*/
 	rational t1 = cancel(s1);
 	rational t2 = cancel(s2);
 	r.s = t1.s^t2.s;