View Compilation Error

0_0_29356320_20535.cpp: In function 'int main()':
0_0_29356320_20535.cpp:16:22: error: 'sizeos' was not declared in this scope
   memset(a,0,sizeos(a));
                      ^
0_0_29356320_20535.cpp:16:23: error: 'memset' was not declared in this scope
   memset(a,0,sizeos(a));
                       ^