View Compilation Error

0_0_20188235_6180.cpp: In function 'int main()':
0_0_20188235_6180.cpp:2:12: error: expected primary-expression before '=' token
 #define pi = 3.1415927;
            ^
0_0_20188235_6180.cpp:8:20: note: in expansion of macro 'pi'
     v =( 4 /  3 )* pi * r * r * r;
                    ^
0_0_20188235_6180.cpp:8:25: error: invalid type argument of unary '*' (have 'double')
     v =( 4 /  3 )* pi * r * r * r;
                         ^