View Compilation Error

0_0_15834038_28489.cpp: In function 'int main()':
0_0_15834038_28489.cpp:5:36: error: 'memset' was not declared in this scope
 #define CLR(x) memset(x,0,sizeof(x))
                                    ^
0_0_15834038_28489.cpp:27:3: note: in expansion of macro 'CLR'
   CLR(c);
   ^