Added some checking of return values for errors

diff --git a/demo/tut1.c b/demo/tut1.c
index 5e2b5bd1f6096794151a622807336769d5183504..0ee017b22696509ea0fcc02e6c5443c4191a873f 100644 (file)
--- a/demo/tut1.c
+++ b/demo/tut1.c
@@ -20,15 +20,26 @@ int aref = AREF_GROUND;     /* more on this later */
 int main(int argc,char *argv[])
 {
        comedi_t *it;
-       int chan=0;
+       int chan = 0;
        lsampl_t data;
-       
-       it=comedi_open("/dev/comedi0");
-       
-       comedi_data_read(it,subdev,chan,range,aref,&data);
-       
-       printf("%d\n",data);
-       
+       int retval;
+
+       it = comedi_open("/dev/comedi0");
+       if(it == NULL)
+       {
+               comedi_perror("comedi_open");
+               return -1;
+       }
+
+       retval = comedi_data_read(it, subdev, chan, range, aref, &data);
+       if(retval < 0)
+       {
+               comedi_perror("comedi_data_read");
+               return -1;
+       }
+
+       printf("%d\n", data);
+
        return 0;
 }