View Compilation Error

0_0_13719690_26733.cpp: In function 'int main()':
0_0_13719690_26733.cpp:35:27: error: 'memset' was not declared in this scope
   memset(num,0,sizeof(num));
                           ^
0_0_13719690_26733.cpp:39:18: error: 'strlen' was not declared in this scope
    l=strlen(ch[i]);
                  ^