Refactor c/beer-song/beer_song.c

c/beer-song/src/beer_song.c

@@ -1,57 +1,59 @@
 #include <stdio.h>
 
 int verse(char* response, int bottles) {
-  if (bottles < 0) {
-    return 0;
-  }
+	if (response == NULL || bottles < 0) {
+		return 0;
+	}
 
-  switch (bottles) {
-  case 0:
-    return sprintf(response,
-		   "No more bottles of beer on the wall, "
-		   "no more bottles of beer.\n"
-		   "Go to the store and buy some more, "
-		   "99 bottles of beer on the wall.\n");
+	switch (bottles) {
+	case 0:
+		return sprintf(response,
+			       "No more bottles of beer on the wall, "
+			       "no more bottles of beer.\n"
+			       "Go to the store and buy some more, "
+			       "99 bottles of beer on the wall.\n");
 
-  case 1:
-    return sprintf(response,
-		   "1 bottle of beer on the wall, "
-		   "1 bottle of beer.\n"
-		   "Take it down and pass it around, "
-		   "no more bottles of beer on the wall.\n");
+	case 1:
+		return sprintf(response,
+			       "1 bottle of beer on the wall, "
+			       "1 bottle of beer.\n"
+			       "Take it down and pass it around, "
+			       "no more bottles of beer on the wall.\n");
 
-  case 2:
-    return sprintf(response,
-		   "2 bottles of beer on the wall, "
-		   "2 bottles of beer.\n"
-		   "Take one down and pass it around, "
-		   "1 bottle of beer on the wall.\n");
+	case 2:
+		return sprintf(response,
+			       "2 bottles of beer on the wall, "
+			       "2 bottles of beer.\n"
+			       "Take one down and pass it around, "
+			       "1 bottle of beer on the wall.\n");
 
-  default:
-    return sprintf(response,
-		   "%d bottles of beer on the wall, "
-		   "%d bottles of beer.\n"
-		   "Take one down and pass it around, "
-		   "%d bottles of beer on the wall.\n",
-		   bottles, bottles, bottles - 1);
+	default:
+		return sprintf(response,
+			       "%d bottles of beer on the wall, "
+			       "%d bottles of beer.\n"
+			       "Take one down and pass it around, "
+			       "%d bottles of beer on the wall.\n",
+			       bottles, bottles, bottles - 1);
 
-  }
+	}
 }
 
 void sing(char *response, int start, int finish) {
-  char *origin = response;
+	if (response == NULL || start < 0 || finish < 0 || start <= finish) {
+		return;
+	}
 
-  for (int bottles = start; bottles >= finish; bottles--) {
-    int charsAdded = verse(response, bottles);
-    response += charsAdded;
+	char *origin = response;
 
-    // Add a newline between verses,
-    // except for the last verse.
-    if (bottles != finish) {
-      sprintf(response, "\n");
-      response += 1;
-    }
-  }
+	for (int bottles = start; bottles >= finish; bottles--) {
+		int charsAdded = verse(origin, bottles);
+		origin += charsAdded;
 
-  response = origin;
+		// Add a newline between verses,
+		// except for the last verse.
+		if (bottles != finish) {
+			sprintf(origin, "\n");
+			origin += 1;
+		}
+	}
 }