View Compilation Error

0_0_24351387_23265.cpp: In function 'int main()':
0_0_24351387_23265.cpp:15:52: error: 'strcmp' was not declared in this scope
  while(scanf("%s",integer)!=EOF&&strcmp(integer,"0")!=0)
                                                    ^
0_0_24351387_23265.cpp:17:29: error: 'strlen' was not declared in this scope
   int index = strlen(integer);
                             ^