/in/foo.c: In function 'main':
/in/foo.c:20:19: error: expected '=', ',', ';', 'asm' or '__attribute__' before '+=' token
         double sun+=h;
                   ^~
/in/foo.c:20:19: error: expected expression before '+=' token
/in/foo.c:22:13: error: 'sun' undeclared (first use in this function)
  double sum=sun+3;
             ^~~
/in/foo.c:22:13: note: each undeclared identifier is reported only once for each function it appears in