View Compilation Error

0_0_28868789_25148.cpp: In function 'int main()':
0_0_28868789_25148.cpp:59:35: error: 'memset' was not declared in this scope
         memset(book,0,sizeof(book));
                                   ^
0_0_28868789_25148.cpp:61:23: error: 'strlen' was not declared in this scope
         len = strlen(s);
                       ^