/in/foo.cc: In function 'bool Comapre(char*, char*, int)':
/in/foo.cc:7:30: error: 'strlen' was not declared in this scope
  for (int j = 0; j < strlen(t); j++)
                              ^
/in/foo.cc: In function 'void Delete(char*, int)':
/in/foo.cc:15:21: error: 'strlen' was not declared in this scope
  for (; j < strlen(s) - 1; j++)
                     ^
/in/foo.cc: In function 'void Insert(char*, int, char)':
/in/foo.cc:21:12: error: 'strlen' was not declared in this scope
  s[strlen(s)] = s[strlen(s) - 1];
            ^
/in/foo.cc: In function 'int main()':
/in/foo.cc:35:32: error: 'strlen' was not declared in this scope
  for (int i = 0; i <= (strlen(s) - strlen(t1) + 1); )
                                ^
/in/foo.cc:48:30: error: 'strlen' was not declared in this scope
  for (int i = 0; i < strlen(s); i++)
                              ^