# include 
# include 
# include 
# include 
# include 
Struct usersdata//build linked list node 
{
char name[20]; 
Char password [20]; 
Struct usersdata * pnext; 

}; 
Typedef struct usersdata users;//structure name change 
Int list_number_count; 
Users * file_read_listnode ()//read from the file to the list 
{
The users * pHead=NULL;//set the head pointer to null pointer does not point to any node 
PEnd users * and * pNew;//set up two Pointers, one to the next node node, another for the node of the last node 
Int list_number_count=0;//is used to determine whether answer the number of nodes is only one 
PEnd=pNew=(users *) malloc (sizeof (users));//for details and new reception space 
The FILE * fl. 
Fl=fopen (" users. TXT ", "r");//opened for read-only files 
Printf (" test \ n "); 
If (fl==NULL)//to determine whether a file pointer position is empty, empty, an error file does not exist 
{
Printf (" can't read or write files \ n "); 
The exit (2); 
} 
While (1)//circulation node 
{
Printf (" test \ n "); 
List_number_count + +; 
If (list_number_count==1)//determine whether for the first node 
{
PNew - & gt; Pnext=NULL;//set up the first node 
Fscanf (fl, "% s % s", pNew - & gt; The name, pNew - & gt; Password);//read the data to the first node 
PEnd=pNew; For the new//end node 
PHead=pNew;//update the head pointer to point to the new node 
} 
The else//is not the first node 
{
if(! Feof (fl))//whether the file to read and write complete, complete the return 1 (i.e., don't read files) 
{
Fscanf (fl, "% s % s", pNew - & gt; The name, pNew - & gt; Password);//read the data from file 
PEnd - & gt; Pnext=pNew;//the node pointer to the next node 
PNew - & gt; Pnext=NULL;//the new node pointer to an empty 
PEnd=pNew;//update the end node position 
PNew=(users *) malloc (sizeof (users));//for the next new node to open a new space 
} 
The else 
Free (pNew);//file to read and write back after the completion of head node pointer 
The fclose (fl); 
Return pHead; 
} 

} 
} 
Void write_Out (users * pHead)//from the list to a file 
{
The users * ptemp;//define a temporary storage head pointer value pointer 
The FILE * fl. 
Fl=fopen (userscopy "text", "w +"); 
Printf (" is from the program output information... \n"); 
Sleep(1000); 
Ptemp=pHead - & gt; Pnext;//to determine whether the original head pointer for temporary pointer no nodes (used for custom only used to access the head node, no value) 
If (ptemp==NULL) 
return;//no nodes return function 
While (ptemp!=NULL)//move at the end of the chain table node pointer is not empty, empty don't have to file out of circulation in the 
{
Fprintf (fl, "% s \ n \ t % s", ptemp - & gt; The name, ptemp - & gt; Password);//will list information written to the file 
Ptemp=ptemp - & gt; Pnext;//update the pointer position 
} 
The fclose (fl); 
return; 
} 
Int main () 
{
The users * pHead; 
Printf (" is copy please later... \n"); 
PHead=file_read_listnode (); 
//write_Out (pHead); 
Printf (" write complete "); 
Sleep(10000); 
return 0; 

}