View Compilation Error

0_0_18539760_5408.cpp: In function 'int main()':
0_0_18539760_5408.cpp:8:41: error: 'memset' was not declared in this scope
 #define CLR(a, b) memset(a, b, sizeof(a))
                                         ^
0_0_18539760_5408.cpp:204:9: note: in expansion of macro 'CLR'
         CLR(vis, false); CLR(lazy, 0);
         ^