View Compilation Error

0_0_22263545_11135.cpp: In function 'int main()':
0_0_22263545_11135.cpp:5:11: error: expected unqualified-id before '=' token
 #define PI=3.1415927
           ^
0_0_22263545_11135.cpp:9:19: note: in expansion of macro 'PI'
      const double PI=3.1415927;
                   ^
0_0_22263545_11135.cpp:5:11: error: expected primary-expression before '=' token
 #define PI=3.1415927
           ^
0_0_22263545_11135.cpp:11:22: note: in expansion of macro 'PI'
          v=(4.0/3.0)*PI*r*r*r;
                      ^