/in/foo.cc: In function 'int main()':
/in/foo.cc:6:12: warning: right operand of comma operator has no effect [-Wunused-value]
   cin>>a,b,c;
            ^
/in/foo.cc:6:13: warning: right operand of comma operator has no effect [-Wunused-value]
   cin>>a,b,c;
             ^
/in/foo.cc:7:12: warning: 'b' is used uninitialized in this function [-Wuninitialized]
   d=a*0.2+b*0.2+c*0.6;
           ~^~~~
/in/foo.cc:7:18: warning: 'c' is used uninitialized in this function [-Wuninitialized]
   d=a*0.2+b*0.2+c*0.6;
                 ~^~~~