View Compilation Error

0_0_32076794_29583.cpp: In function 'int main()':
0_0_32076794_29583.cpp:6:36: error: 'memset' was not declared in this scope
 #define clr(x) memset(x,0,sizeof(x))
                                    ^
0_0_32076794_29583.cpp:22:3: note: in expansion of macro 'clr'
   clr(v); clr(w); clr(f);
   ^