Sum of all elements in CvArr with OpenCV C API -

using opencv's, c language based api, need calculate sum of elements in opencv array. use sum(1) method. below have tried.

/* rgb1 opencv array */ cvscalar cvsum( const cvarr* rgb1); printf("%lf", cvscalar.val); 

but compiler error error: expected primary-expression before ‘.’ token.

'val' is array of doubles. need access via val[0], , printf using %f

you have bug. wrote in not valid c code.
should this:

cvscalar sum = cvsum(rgb1); printf("%f", sum.val[0]); 

or if don't want variable:

printf("%f", cvsum(rgb1).val[0]);