Use bool for two-state variable.

src/gribapi_utilities.c

@@ -712,7 +712,12 @@ void gribapiGetGrid(grib_handle *gh, grid_t *grid)
     }
 
   if ( gridtype == GRID_GAUSSIAN || gridtype == GRID_LONLAT || gridtype == GRID_PROJECTION || gridtype == GRID_LCC )
-    GRIB_CHECK(grib_get_long(gh, "uvRelativeToGrid", &grid->uvRelativeToGrid), 0);
+    {
+      long temp;
+      GRIB_CHECK(grib_get_long(gh, "uvRelativeToGrid", &temp), 0);
+      assert(temp == 0 || temp == 1);
+      grid->uvRelativeToGrid = (bool)temp;
+    }
 
   grid->type  = gridtype;
   grid->projtype  = projtype;

src/grid.c

@@ -3941,7 +3941,7 @@ void gridDefUvRelativeToGrid(int gridID, int uvRelativeToGrid)
   if ( gridptr->uvRelativeToGrid != uvRelativeToGrid )
     {
       gridMark4Update(gridID);
-      gridptr->uvRelativeToGrid = uvRelativeToGrid;
+      gridptr->uvRelativeToGrid = (bool)uvRelativeToGrid;
     }
 }
 

src/grid.h

@@ -104,7 +104,8 @@ struct grid_t {
   int     np;                     /* number of parallels between a pole and the equator */
   bool    lcomplex;
   bool    hasdims;
-  long uvRelativeToGrid;           /* Some models deliver wind U,V relative to the grid-cell */
+  /* Some models deliver wind U,V relative to the grid-cell */
+  bool uvRelativeToGrid;
   struct gridaxis_t x;
   struct gridaxis_t y;
   const struct gridVirtTable *vtable;