View Compilation Error

0_0_22196867_31920.cpp: In function 'int main()':
0_0_22196867_31920.cpp:45:33: error: 'memset' was not declared in this scope
         memset(tag,0,sizeof(tag));
                                 ^
0_0_22196867_31920.cpp:47:31: error: 'strlen' was not declared in this scope
         for(i = 1;i < strlen(s);i ++)   
                               ^