View Compilation Error

0_0_37561911_13464.cpp: In function 'int main()':
0_0_37561911_13464.cpp:34:20: error: 'strlen' was not declared in this scope
         if(strlen(a)==0)break;
                    ^
0_0_37561911_13464.cpp:36:29: error: 'memset' was not declared in this scope
         memset(a,0,sizeof(a));
                             ^
0_0_37561911_13464.cpp:39:20: error: 'strlen' was not declared in this scope
         if(strlen(a)==0)break;
                    ^
0_0_37561911_13464.cpp:41:29: error: 'memset' was not declared in this scope
         memset(a,0,sizeof(a));
                             ^