foo.cc: In function ‘int main()’:
foo.cc:10:9: error: ‘memset’ was not declared in this scope
   10 |         memset(a,0,sizeof(a));
      |         ^~~~~~
foo.cc:2:1: note: ‘memset’ is defined in header ‘<cstring>’; did you forget to ‘#include <cstring>’?
    1 | #include <iostream>
  +++ |+#include <cstring>
    2 |