C language has a head loop single linked list

/************************************************************************* > File name:singlelinetable.c > Au thor:zshh0604 > Mail: [email protected] > Created time:2014 October 15 Wednesday 11:34 08 Sec. ********************* /#include <stdio.h> #include <stdlib.h> #include  <string.h>/*** * Circular single linked list. * Student Structure: *id: Student number *name: Student name *math: Score *next: Point to next student struct */typedef struct student {int id; char name[20];int math;s Truct student * NEXT;} stu;typedef int Cmp_stu (const void *, const void *);/**** * Function Function: * Create a head node. * Function parameter: *void. * Return value of function: * Returns the head node pointer. */stu * Create (void) {stu *head = null;stu *p = Null;stu *new = null;int tmpid = 0; char tmpname[20];int tmpmath;head = (stu *) malloc (sizeof (STU)), if (head = = NULL) {printf ("Failed to allocate STU address space!!! \ n "); return NULL;}   Head->id = 0;strncpy (Head->name, "n"); Head->math = 0;//head->next = NULL;   Single-linked list head->next = head;             A single linked list with head loops P = head; When the head is created, it shouldPoint the pointer to the head. while (1) {new = (stu*) malloc (sizeof (STU)), if (new==null) {printf ("malloc new error\n"); return NULL;} Tmpid++;if (Tmpid = = 3) {break;} New->id = tmpid;printf ("\nname="), scanf ("%s", Tmpname), strncpy (new->name,tmpname,20);p rintf ("math="); scanf ( "%d", &tmpmath); new->math = Tmpmath;p->next = new;  p = new;//new->next = NULL;  Single-linked list new->next = head; A single-linked list with head loops}return head;} /*** * Function: * Print out the data in a single linked list. * Function Parameter: *head is the head of the linked list. * Return Value: * No return value */void printf_list (Stu *head) {stu *tmp = Null;int i = 0;if (head== NULL) {return;} TMP = head->next; #if1//With Head loop single-linked list while (Tmp!=head) {i++;p rintf ("name =%s\n", tmp->name);p rintf ("math =%d\n", tmp- >math); tmp = Tmp->next;} #elsewhile (Tmp!=null)//single-linked list {i++;p rintf ("name =%s\n", tmp->name);p rintf ("math =%d\n", tmp->math); tmp = tmp-> Next; #endifprintf ("Len =%d\n", i);} /***** * Function Function: * comparison function. * Function Parameter: * * function return value: * Returns 0 indicates success.  * Return 1 indicates failure? * */int CMP (const void * data, const void * key) {Stu * head = null;int * Tmpkey =null;head = (stu*) data;tmpkey= (int*) key;//printf ("Head->id =%d, Tmpkey =%d", ((stu*) data)->id, *tmpkey); if (Head->id = = *tmpkey ) {return 0;} return 1;} /**** * Function Function: * Find data in one node. * Function Parameter: * * function return value: * Return 0 Lookup succeeded, return 1 lookup failed. */void * FIND_STU (stu* head,cmp_stu* cmps, const void *key) {stu * tmp = NULL;TMP = head->next;if (key = = NULL) {return NU LL;} #if 1//Circular single-linked list if (CMPS (const void *) head, (const void *) key) = = 0) {printf ("name =%s\n", tmp->name);p rintf ("math =%d\n" , Tmp->math); return tmp;} while (tmp! = head) {if (CMPS (const void *) TMP, (const void *) key) (==0) {printf ("name =%s\n", tmp->name);p rintf ("math =% D\n ", Tmp->math); return tmp;} TMP = Tmp->next;} #else//single-linked list while (tmp! = NULL) {if (CMPS (const void *) TMP, (const void *) key) ==0) {printf ("name =%s\n", tmp->name);p RI NTF ("math =%d\n", tmp->math); return tmp;} TMP = tmp->next; #endifreturn NULL;} /*** * Function Function: * Insert node. * Function Parameter: * Head: The node in the linked list. * NEW: The node that needs to be inserted. * Return value of function: * Returns 0 indicates successful insertion. * Return 1 indicates an insert failure. */int Insert_tool (stu* Head, stu* new) {if (head==null| | New = NULL) {return 1;} #if 1//Cycle single-link list if (Head->next = = head) {head->next = New;new->next = head;} #else//single-linked list if (Head->next = = null) {Head->next = New;new->next = null;} #endifnew->next = Head->next;head->next = New;return 0;} /*** * Function Function: * Compare by name.  * Function Parameter: * Data, key is the value to look up in the data. * Return value of function: * Returns 0 success. 1 failed to return. */int cmp_name (const void *data, const void *key) {stu *tmp = Null;char *tmpname = null;if (data== NULL | | key = NULL) {Retu RN 1;} TMP = (stu *) Data;tmpname = (char *) key;if (strncmp (tmp->name,tmpname) ==0) {return 0;} return 1;} /*** * * Function function: * Insert a node into the linked list. * Function parameter: *head: The head node of the linked list. *name: The name of the node to view. * Function return Value: * Returns 0 insert succeeded. * Return 1 Insert failed. */int Insert_stu (stu* Head,char *name) {stu * tmp = null;stu * new = Null;char Tmpname[20];int tmpmath;tmp = (stu *) Find_st U (head,cmp_name,name), if (tmp = = NULL) {printf ("The classmate was not found \"); return 1;} New = (stu*) malloc (sizeof (STU));p rintf ("Name="), scanf ("%s", Tmpname), strncpy (new->name,tmpname,20);p rintf (" Math= "); scanf ("%d ", &tmpmath); NEW-&GT;math = Tmpmath;new->id = 10;insert_tool (tmp,new); return 0;} /** * Function Function: * Delete the established node. * Parameters: * Head: List header * Name: To delete the student's name. * return value. * 0 returns success. 1 failed to return. */int Delete_stu (stu * Head,char *name) {stu * back = Null;stu * p = null;p = head->next; #if 1//Circular single-link list if (strcmp (p-&gt ; name,name) ==0) {Head->next = P->next;p->next = Null;free (p); return 0;} while (P! = head) {back = P; p = p->next; if (strcmp (p->name,name) = = 0) {Back->next = P->next;p->next = Null;f REE (p); return 0;}} #else//single-linked list while (p!=null) {back = P; p = p->next; if (strcmp (p->name,name) = = 0) {Back->next = P->next;p->nex t = Null;free (p); return 0;} #endifreturn 1;} /*** * Function function: * Destroy linked list. * Parameters of the function: * The head of the linked list. * The return value of the function *0 indicates a successful return. 1 indicates a failure to return. */int destory_list (stu* head) {stu *tmp;stu *p;p = Head->next;while (p!=head) {tmp = P; p = P->next;tmp->next = null;printf ("name =%s", tmp->name); free (TMP);}} int main (void) {int i = 2;stu * head = Null;head = Create ();p rintf_list (head); Find_stu (head,cmp,&i); Insert_stU (head, "BB");p rintf_list (head);p rintf ("----------------------\ n");d Estory_list (head), head = Null;printf_list ( Head);p rintf ("---------------------\ n");}

C language has a head loop single linked list