View Compilation Error

0_0_27865183_8611.cpp: In function 'void KM()':
0_0_27865183_8611.cpp:12:36: error: 'memset' was not declared in this scope
 #define clr(x) memset(x,0,sizeof(x))
                                    ^
0_0_27865183_8611.cpp:150:5: note: in expansion of macro 'clr'
     clr(lx); clr(ly);
     ^