Return the found index instead of using the pointer

src/utilities.h

@@ -27,12 +27,11 @@
  * @param x The value to find
  * @param array The array to search
  * @param n The length of the array
- * @param index The found index
  *
- * Set -1 and n for x below and above the array edge values respectively.
+ * Return -1 and n for x below and above the array edge values respectively.
  */
-INLINE static void find_value_in_monotonic_array(
-    const float x, const float *array, const int n, int *index) {
+INLINE static int find_value_in_monotonic_array(
+    const float x, const float *array, const int n) {
 
     int index_mid, index_low = 0, index_high = n;
 
@@ -49,11 +48,11 @@ INLINE static void find_value_in_monotonic_array(
 
     // Set index with the found index_low or an error value if outside the array
     if (x < array[0])
-        *index = -1;
+        return -1;
     else if (array[n-1] <= x)
-        *index = n;
+        return n;
     else
-        *index = index_low;
+        return index_low;
 }
 
 #endif /* SWIFT_UTILITIES_H */

tests/testUtilities.c

@@ -37,28 +37,28 @@ int main() {
 
     // Typical value
     x = 42.42f;
-    find_value_in_monotonic_array(x, array, n, &index);
+    index = find_value_in_monotonic_array(x, array, n);
     if (index != 42) {
         error("Failed with a typical value ");
     }
 
     // Value on array element
     x = 33.f;
-    find_value_in_monotonic_array(x, array, n, &index);
+    index = find_value_in_monotonic_array(x, array, n);
     if (index != 33) {
         error("Failed with an array element ");
     }
 
     // Value below array
     x = -123.f;
-    find_value_in_monotonic_array(x, array, n, &index);
+    index = find_value_in_monotonic_array(x, array, n);
     if (index != -1) {
         error("Failed with a value below the array ");
     }
 
     // Value above array
     x = 123.f;
-    find_value_in_monotonic_array(x, array, n, &index);
+    index = find_value_in_monotonic_array(x, array, n);
     if (index != n) {
         error("Failed with a value above the array ");
     }
@@ -66,7 +66,7 @@ int main() {
     // Array slice with typical value
     x = 9.81f;
     n = 10;
-    find_value_in_monotonic_array(x, array + 5, n, &index);
+    index = find_value_in_monotonic_array(x, array + 5, n);
     if (index != 4) {
         error("Failed with an array slice ");
     }