View Compilation Error

0_0_18866346_8037.cpp:2:9: error: no macro name given in #define directive
 #define 
         ^
0_0_18866346_8037.cpp:3:1: error: expected unqualified-id before '{' token
 {pi 3.1415927}
 ^
0_0_18866346_8037.cpp: In function 'int main()':
0_0_18866346_8037.cpp:9:18: error: 'pi' was not declared in this scope
   double t=r*r*r*pi*4/3;
                  ^