该函数要求用户输入要搜索的值，然后删除列表中的所有匹配值。
程序运行完美，但我无法找出一种简单/优雅的方法来分离“第一个节点”，“最后一个节点”和“中间节点”的案例。
请帮助我使它更优雅和可读。
我会发布相关的代码块，然后是整个程序。
在相关函数中，以下代码块是我正在使用的switch-case结构的一部分（如果用户输入'v'，则表示搜索'value'并删除，而不是'删除第一个node'或'删除最后一个节点'）
case 'v':
printf("\n\tEnter value to delete:\t");
scanf("%d",&value);
r=q;
if(!q)//If linked list is empty
{
printf("\n\t\tLinked list is EMPTY\n");
return;
}
else if(!(q->next))//If linked list consists of only one node
{
if((q->data)==value)
{
free(q);
printf("\nValue found and deleted in position 1\n");
count=1;
}
}
else//If linked list consists of more than one node
{
for(i=1;q;i++)
{
if(q->data==value)
{
if(i==1)//for first node
{
q=q->next;
free(r);
*pp=q;
printf("\nValue found and deleted in position 1\n");
count=1;
}
else//for the rest of the nodes
{
printf("\nValue found and deleted in position %d\n",i);
r->next=q->next;
temp=q;
q=q->next;
free(temp);
count++;
}
}
else
{
r=q;
q=q->next;
}
}
}
if(count==0)//If no matches are found
printf("Value not found");
break;
完成计划：
#include <stdio.h>
#include <stdlib.h>
struct node
{
int data;
struct node *next;
};
int count(struct node *);
void traverse(struct node *);
void insert(struct node **);
void delete(struct node **);
void deletelist(struct node **);
int main()
{ char choice;
struct node *head, **tohead;
head=(struct node *)malloc (sizeof(struct node));
head=NULL;
tohead=&head;
do
{
printf("\nChoose operation to perform:\n");
printf("\tCount number of nodes(c):\n");
printf("\tInsert a node(i)\n");
printf("\tDelete a node(d)\n");
printf("\tDelete the list(D)\n");
printf("\tShow currenct linked list(s)\n");
printf("\tQuit without saving changes(q):\t");
scanf(" %c",&choice);
switch(choice)
{
case 'i':
insert(tohead);
break;
case 'c':
printf("\nList count is %d\n",count(head));
break;
case 's':
traverse(head);
break;
case 'q':
printf("QUITTING\n");
break;
case 'd':
delete(tohead);
break;
case 'D':
deletelist(tohead);
break;
default:
printf("\n\tINVALID CHOICE\n");
}
}while(choice!='q');
}
int count(struct node *p)
{
int i;
for(i=0;p;i++)
p=p->next;
return i;
}
void traverse(struct node *p)
{
printf("\nLinked list looks like: ");
if(!p)
{
printf("nothing. It's EMPTY");
}
else
{ while(p)
{
printf("%d\t",p->data);
p=p->next;
}
}
printf("\n");
}
void insert(struct node **pp)
{
int value,position;
struct node *q;
q=*pp;
struct node *newnode=(struct node *)malloc(sizeof(struct node));
printf("Insert what number?:\t");
scanf("%d",&value);
printf("In what position? Push '0' for last,'1' for first");
printf("\n\t\tOR\nenter position no.:\t");
scanf("%d",&position);
newnode->data=value;
if(position==1)
{ newnode->next=q;
*pp=newnode;
}
else if(position==0)
{
if(!q)
{
newnode->next=q;
*pp=newnode;
}
else
{
while(q->next)
q=q->next;
q->next=newnode;
newnode->next=NULL;
}
}
else if((position>1)&&(position<=count(q)+1))
{
int i;
for(i=1;i<position-1;i++)
q=q->next;
newnode->next=q->next;
q->next=newnode;
}
else
printf("\n\t\tINVALID POSITION\n");
}
void delete(struct node **pp)
{
struct node *q,*r,*temp;
q=*pp;
int i,count=0,value,position;
char choice;
printf("\n\tPush 'v' to delete a specific value");
printf("\n\t\t\tOR");
printf("\n\t'1' to delete the first value");
printf("\n\t'0' to delete the last value:\t");
scanf(" %c",&choice);
if(q==NULL)
{ printf("List is EMPTY\n");
return;
}
switch(choice)
{
case '1':
*pp=q->next;
free(q);
break;
case '0':
while(q->next!=NULL)
{
r=q;
q=q->next;
}
r->next=NULL;
free(q);
break;
case 'v':
printf("\n\tEnter value to delete:\t");
scanf("%d",&value);
r=q;
if(!q)//If linked list is empty
{
printf("\n\t\tLinked list is EMPTY\n");
return;
}
else if(!(q->next))//If linked list consists of only one node
{
if((q->data)==value)
{
free(q);
printf("\nValue found and deleted in position 1\n");
count=1;
}
}
else//If linked list consists of more than one node
{
for(i=1;q;i++)
{
if(q->data==value)
{
if(i==1)//for first node
{
q=q->next;
free(r);
*pp=q;
printf("\nValue found and deleted in position 1\n");
count=1;
}
else//for the rest of the nodes
{
printf("\nValue found and deleted in position %d\n",i);
r->next=q->next;
temp=q;
q=q->next;
free(temp);
count++;
}
}
else
{
r=q;
q=q->next;
}
}
}
if(count==0)//If no matches are found
printf("Value not found");
break;
default:
printf("\nBad choice");
}return;
}
void deletelist(struct node **pp)
{
struct node *p,*temp;
p=*pp;
while(p)
{
temp=p;
p=p->next;
free(temp);
}
*pp=NULL;
printf("\nLIST DELETED\n");
}
答案 0 :(得分：0)
void filter(struct node **pp, int value){
struct node *curr, *prev=NULL, *tmp;
curr = *pp;
if(!curr)
return ;
tmp = curr;
while(tmp){
if(tmp->data != value){
curr->data = tmp->data;
prev = curr;
curr = curr->next;
}
tmp = tmp->next;
}
deletelist(&curr);
if(prev){
prev->next = NULL;
} else {
*pp = NULL;
}
}