fix usage with C++
#ifndef __spglib_H__
#define __spglib_H__
+#ifdef __cplusplus
+extern "C" {
+#endif
/* SPGCONST is used instead of 'const' so to avoid gcc warning. */
/* However there should be better way than this way.... */
#ifndef SPGCONST
@@ -481,4 +484,7 @@ void spg_get_neighboring_grid_points(int relative_grid_points[],
/* Return 0 if failed */
int spg_niggli_reduce(double lattice[3][3], const double symprec);
+#ifdef __cplusplus
+}
+#endif
#endif
