1 files changed, 13 insertions, 1 deletions
diff --git a/h/sort.h b/h/sort.h
index 98bee8f..8440425 100644
--- a/h/sort.h
+++ b/h/sort.h
@@ -1,4 +1,6 @@
 
+#ifndef SORT_H
+
 /*
  * Copyright 1996 - 2010 Graeme W. Gill
  * All rights reserved.
@@ -7,13 +9,17 @@
  * see the License2.txt file for licencing details.
  */
 
+#ifdef __cplusplus
+	extern "C" {
+#endif
+
 /*
  * Heapsort macro - sort smallest to largest.
  * Heapsort is guaranteed nlogn, doesn't need any
  * extra storage, but often isn't as fast as quicksort.
  */
 
-/* Need to #define HEAP_COMPARE(A,B) so it returns true if A < B */
+/* To sort ascenting, need to #define HEAP_COMPARE(A,B) so it returns true if A < B */
 /* Note that A will be ARRAY[a], and B will be ARRAY[b] where a and b are indexes. */
 /* TYPE should be the type of each entry of the ARRAY */
 #define HEAPSORT(TYPE,ARRAY,NUMBER) \
@@ -60,3 +66,9 @@
 			}	\
 		}
 
+#ifdef __cplusplus
+	}
+#endif
+
+#define SORT_H
+#endif /* SORT_H */