View Compilation Error

0_0_36787512_7349.cpp: In function 'int main()':
0_0_36787512_7349.cpp:5:38: error: 'memset' was not declared in this scope
 #define mem(a) memset(a, 0, sizeof(a))
                                      ^
0_0_36787512_7349.cpp:26:3: note: in expansion of macro 'mem'
   mem(vis);
   ^