View Compilation Error

0_0_32485436_29609.cpp: In function 'int main()':
0_0_32485436_29609.cpp:14:16: error: 'g' was not declared in this scope
         memset(g , 0 , sizeof(g));
                ^
0_0_32485436_29609.cpp:14:33: error: 'memset' was not declared in this scope
         memset(g , 0 , sizeof(g));
                                 ^