循环链表 节点释放释放

#include
#include
#include "define.h"


using namespace std;


int main(int argc, char *argv[])
{
//创建单循环链表
node *head_cycle = NULL;
cout<<"create the cycle list(by queue):"< head_cycle = createlist_cycle();
deletelist(head_cycle);



#include
#include
#include "define.h"

using namespace std;

int main(int argc, char *argv[])
{
//创建单循环链表
node *head_cycle = NULL;
cout<<"create the cycle list(by queue):"< head_cycle = createlist_cycle();
deletelist(head_cycle);


//创建链表，并返回链表数目
node *head = NULL;
cout<<"create the single list(by queue):"< head = createlist();
cout<<"print the single list:"< printlist(head);


//计算链表的长度
int n = linklength (head);
cout<<"the length of the single list is:"<

//查找输入元素的位置
char x;
printf("Please input an element and return the location of the element!\n");
scanf("%c", &x);
fflush(stdin); //清空标准输入缓冲区，方便下次使用 如果有多个输入语句时 加入fflush用来清空缓冲区
locate(head, x);

//在链表中插入元素
cout<<"please input one char and one num(please insert space between the two chracters):"< char i;
int num;
scanf("%c %d", &i, &num);
fflush(stdin);
insertlist(head, i, num, n);

//链表逆序输出
printf("\nOutput the inversing list!\n");
inverselist(head);

deletelist(head);
return true;

}

struct node_link *createlist_cycle()
{
char c;
node *tail;
node *head = NULL;
while((c=getchar()) != '\n')
{
Node p = (Node )malloc(sizeof(node));
//Node p = (Node )malloc(sizeof(Node));
if(p == NULL)
{
printf("malloc failed!\n"); //申请内存失败
return false;
}
p->data = c;
if(head==NULL)
{
head = p;
tail = p;
}
else
{
tail->next = p;
tail = p;
}
tail->next = NULL; //每次都要重新申请，并释放，成对出现
}
tail->next = head;

Node head_insert = head;
while(head_insert)
{
cout<data<<"->";
head_insert = head_insert->next;

if(head_insert==head)
{
break;
}
}

return head;
}

struct node_link *createlist()
{
char c;
node *tail;
node *head = NULL;
while((c=getchar()) != '\n')
{
Node p = (Node )malloc(sizeof(node));
if(p == NULL)
{
printf("malloc failed!\n"); //申请内存失败
return false;
}
p->data = c;
if(head==NULL)
{
head = p;
tail = p;
}
else
{
tail->next = p;
tail = p;
}
tail->next = NULL; //每次都要重新申请，并释放，成对出现
}
return head;
}

int linklength(node *head)
{
if(head == NULL)
return 0;
else
return( 1+linklength(head->next) );
//return(head);
//return(n);

}

void printlist(node *head)
{
if(head==NULL && flag==0)
cout<<"the list is null!"< else
{
flag = 1; //设置标志位进行判断
cout<data<<"->";
if(head->next==NULL)
{
cout< return;
}

printlist(head->next);
}
}

int locate(node *head, char x)
{
int n=0;
while (head!=NULL && head->data!=x)
{
head=head->next;
n++;
}
if(head==NULL)
return(-1);
else
cout<<"the location of the element is "< return(n+1);
}
struct node_link *inverselist(node *head)
{
Node head_node;
Node p, q, r;
p = head;
q = p->next;
while(q!=NULL)
{
r = q->next;
q->next = p;
p = q;
q = r;
}
head->next = NULL;
head_node = p;

head = p;
while(head)
{
cout<data<<"->";
head = head->next;
}
cout<
return head_node;
}
int insertlist(node *head,char x, int i, int len) //一定要把头指针传过来
{
Node head_insert;
Node p = new node[];
p->data = x;
int j = 1;
if(i==1) //要考虑到插入到头结点和插入到尾结点的不同
{
p->next = head;
head = p;
head_insert = head;
}

else if(i==(len+1)) //多用小括号，防止出错
{
head_insert = head;

int cnt = 0;
while(cnt!=len-2)
{
head = head->next;
}
head->next = p;
p->next = NULL; //不能保证tail指针也能传进来 插入与建立链表是两码事
}

else if(i>=len+1)
{
cout<<"The parameter of location is incorrect!"< return 0;
}

else //第三种情况 插入到中间位置
{
head_insert = head;

while(jnext!=NULL)
{
head=head->next;
j++;
if(j==i)
{
p->next = head->next;
head->next = p;
}
//else
// cout<<"The parameter of location is incorrect!"<
}

}

//return head_insert;
cout<<"after inserting, print the single list:"< while(head_insert)
{
cout<data<<"->";
head_insert = head_insert->next;
}

return 1;
}

void deletelist(node *head)
{
Node p, q;
p = head->next;

while(p!=head) //
{
q = p->next;
free(p); //
p = q;
}

free(head);
head = NULL;
//cout<<"head == NULL"< }
//创建链表，并返回链表数目
node *head = NULL;
cout<<"create the single list(by queue):"< head = createlist();
cout<<"print the single list:"< printlist(head);




//计算链表的长度
int n = linklength (head);
cout<<"the length of the single list is:"<



//查找输入元素的位置
char x;
printf("Please input an element and return the location of the element!\n");
scanf("%c", &x);
fflush(stdin);    //清空标准输入缓冲区，方便下次使用 如果有多个输入语句时 加入fflush用来清空缓冲区
locate(head, x);


//在链表中插入元素
cout<<"please input one char and one num(please insert space between the two chracters):"< char i;
int num;
scanf("%c %d", &i, &num);
fflush(stdin);
insertlist(head, i, num, n);


//链表逆序输出
printf("\nOutput the inversing list!\n");
inverselist(head);


deletelist(head);
return true;


}


struct node_link *createlist_cycle()
{
char c;
node *tail;
node *head = NULL;
while((c=getchar()) != '\n')
{
Node p = (Node )malloc(sizeof(node));
//Node p = (Node )malloc(sizeof(Node));
if(p == NULL)
{
  printf("malloc failed!\n");           //申请内存失败
  return false;  
}
p->data = c;
if(head==NULL)
{
head = p;
tail = p;
}
else
{
tail->next = p;
tail = p;
}
tail->next = NULL;                       //每次都要重新申请，并释放，成对出现
}
tail->next = head;

Node head_insert = head;
while(head_insert)      
{
cout<data<<"->";
head_insert = head_insert->next;


if(head_insert==head)
{
break;
}
}


return head;
}


struct node_link *createlist()
{
char c;
node *tail;
node *head = NULL;
while((c=getchar()) != '\n')
{
Node p = (Node )malloc(sizeof(node));
if(p == NULL)
{
  printf("malloc failed!\n");           //申请内存失败
  return false;  
}
p->data = c;
if(head==NULL)
{
head = p;
tail = p;
}
else
{
tail->next = p;
tail = p;
}
tail->next = NULL;                       //每次都要重新申请，并释放，成对出现
}
return head;
}


int linklength(node *head)
{
if(head == NULL)
return 0;
else
return( 1+linklength(head->next) );
//return(head);
  //return(n);


}


void printlist(node *head)
{
if(head==NULL && flag==0)
cout<<"the list is null!"< else      
{
flag = 1;  //设置标志位进行判断
cout<data<<"->";
if(head->next==NULL)
{
cout< return;
}

printlist(head->next);
}
}


int locate(node *head, char x)
{
int n=0;
while (head!=NULL && head->data!=x)
  {
  head=head->next;
n++;
  }
  if(head==NULL)
  return(-1);
  else
cout<<"the location of the element is "<   return(n+1);
}
struct node_link *inverselist(node *head)
{
Node head_node;
Node p, q, r;
p = head;
q = p->next;
while(q!=NULL)      
{
r = q->next;
q->next = p;
p = q;
q = r;
}
head->next = NULL;
head_node = p;


head = p;
while(head)      
{
cout<data<<"->";
head = head->next;
}
cout<

return head_node;
}
int insertlist(node *head,char x, int i, int len) //一定要把头指针传过来
{
Node head_insert;
Node p = new node[];
p->data = x;
int j = 1;
if(i==1)  //要考虑到插入到头结点和插入到尾结点的不同
{
p->next = head;
head = p;
head_insert = head;
}


else if(i==(len+1)) //多用小括号，防止出错
{
head_insert = head;


int cnt = 0;
while(cnt!=len-2)
{
head = head->next;
}
head->next = p;
p->next = NULL;  //不能保证tail指针也能传进来 插入与建立链表是两码事
}


else if(i>=len+1)
{
cout<<"The parameter of location is incorrect!"< return 0;
}


else  //第三种情况 插入到中间位置
{
head_insert = head;


while(jnext!=NULL)
{
    head=head->next;
    j++;
    if(j==i)
      {
p->next = head->next;
head->next = p;
      }
//else 
    // cout<<"The parameter of location is incorrect!"<

}

}


//return head_insert;
cout<<"after inserting, print the single list:"< while(head_insert)      
{
cout<data<<"->";
head_insert = head_insert->next;
}

return 1;
}


void deletelist(node *head)
{
Node p, q;
p = head->next;

while(p!=head)   // 
{
q = p->next;
free(p);     //
p = q;
}


free(head);
head = NULL;
//cout<<"head == NULL"< }

问题1:  申请多少内存，再释放多少内存，虽然话是这么说，但是一定要亲力亲为

Node p = (Node )malloc(sizeof(node));
//Node p = (Node )malloc(sizeof(Node));

导致节点无法释放，申请的一个结构体，与申请一个结构体指针是不同的

问题2：

sanf函数的使用，要注意

两次使用需要清空缓存区，

下图所示的错误并不是 不能无从下手的！