View Compilation Error

0_0_18707369_19827.cpp: In constructor 'Mat::Mat(int)':
0_0_18707369_19827.cpp:14:25: error: 'memset' was not declared in this scope
   memset(v, 0, sizeof(v));  
                         ^
0_0_18707369_19827.cpp: In member function 'void Mat::init(ll)':
0_0_18707369_19827.cpp:18:25: error: 'memset' was not declared in this scope
   memset(v, 0, sizeof(v));
                         ^