View Compilation Error

0_0_17160414_28652.cpp: In member function 'void ST::init()':
0_0_17160414_28652.cpp:39:35: error: 'memset' was not declared in this scope
         memset(vis, 0, sizeof(vis));
                                   ^
0_0_17160414_28652.cpp: In member function 'void BIT::init()':
0_0_17160414_28652.cpp:84:29: error: 'memset' was not declared in this scope
         memset(C,0,sizeof(C));
                             ^
0_0_17160414_28652.cpp: In function 'void init(int)':
0_0_17160414_28652.cpp:139:29: error: 'memset' was not declared in this scope
     memset(sum,0,sizeof(sum));
                             ^