有大佬让我重新把整个C语言学一遍 -

/*
单链表的增、删
*/
#include<stdlib.h>
#include <stdio.h>
void create();
void display();
void insert_begin();
void insert_end();
void insert_pos();
void delete_begin();
void delete_end();
void delete_pos();
struct node
{
int info;
struct node *next;
};
struct node *start=NULL;
int main()
{
int choice;
while(1){
printf("n MENU n");
printf("n 1.Create n");
printf("n 2.Display n");
printf("n 3.Insert at the beginning n");
printf("n 4.Insert at the end n");
printf("n 5.Insert at specified position n");
printf("n 6.Delete from beginning n");
printf("n 7.Delete from the end n");
printf("n 8.Delete from specified position n");
printf("n 9.Exit n");
printf("n--------------------------------------n");
printf("Enter your choice:t");
scanf("%d",&choice);
switch(choice)
{
case 1:
create();
break;
case 2:
display();
break;
case 3:
insert_begin();
break;
case 4:
insert_end();
break;
case 5:
insert_pos();
break;
case 6:
delete_begin();
break;
case 7:
delete_end();
break;
case 8:
delete_pos();
break;
case 9:
exit(0);
break;
default:
printf("n Wrong Choice:n");
break;
}
}
return 0;
}
void create()
{
struct node *temp,*ptr;
temp=(struct node *)malloc(sizeof(struct node));
if(temp==NULL)
{
printf("nOut of Memory Space:n");
exit(0);
}
printf("nEnter the data value for the node:t");
scanf("%d",&temp->info);
temp->next=NULL;
if(start==NULL)
{
start=temp;
}
else
{
ptr=start;
while(ptr->next!=NULL)
{
ptr=ptr->next;
}
ptr->next=temp;
}
}
void display()
{
struct node *ptr;
if(start==NULL)
{
printf("nList is empty:n");
return;
}
else
{
ptr=start;
printf("nThe List elements are:n");
while(ptr!=NULL)
{
printf("%dt",ptr->info );
ptr=ptr->next ;
}
}
}
void insert_begin()
{
struct node *temp;
temp=(struct node *)malloc(sizeof(struct node));
if(temp==NULL)
{
printf("nOut of Memory Space:n");
return;
}
printf("nEnter the data value for the node:t" );
scanf("%d",&temp->info);
temp->next =NULL;
if(start==NULL)
{
start=temp;
}
else
{
temp->next=start;
start=temp;
}
}
void insert_end()
{
struct node *temp,*ptr;
temp=(struct node *)malloc(sizeof(struct node));
if(temp==NULL)
{
printf("nOut of Memory Space:n");
return;
}
printf("nEnter the data value for the node:t" );
scanf("%d",&temp->info );
temp->next =NULL;
if(start==NULL)
{
start=temp;
}
else
{
ptr=start;
while(ptr->next !=NULL)
{
ptr=ptr->next ;
}
ptr->next =temp;
}
}
void insert_pos()
{
struct node *ptr,*temp;
int i,pos;
temp=(struct node *)malloc(sizeof(struct node));
if(temp==NULL)
{
printf("nOut of Memory Space:n");
return;
}
printf("nEnter the position for the new node to be inserted:t");
scanf("%d",&pos);
printf("nEnter the data value of the node:t");
scanf("%d",&temp->info) ;
temp->next=NULL;
if(pos==0)
{
temp->next=start;
start=temp;
}
else
{
for(i=0,ptr=start;i<pos-1;i++) { ptr=ptr->next;
if(ptr==NULL)
{
printf("nPosition not found:[Handle with care]n");
return;
}
}
temp->next =ptr->next ;
ptr->next=temp;
}
}
void delete_begin()
{
struct node *ptr;
if(ptr==NULL)
{
printf("nList is Empty:n");
return;
}
else
{
ptr=start;
start=start->next ;
printf("nThe deleted element is :%dt",ptr->info);
free(ptr);
}
}
void delete_end()
{
struct node *temp,*ptr;
if(start==NULL)
{
printf("nList is Empty:");
exit(0);
}
else if(start->next ==NULL)
{
ptr=start;
start=NULL;
printf("nThe deleted element is:%dt",ptr->info);
free(ptr);
}
else
{
ptr=start;
while(ptr->next!=NULL)
{
temp=ptr;
ptr=ptr->next;
}
temp->next=NULL;
printf("nThe deleted element is:%dt",ptr->info);
free(ptr);
}
}
void delete_pos()
{
int i,pos;
struct node *temp,*ptr;
if(start==NULL)
{
printf("nThe List is Empty:n");
exit(0);
}
else
{
printf("nEnter the position of the node to be deleted:t");
scanf("%d",&pos);
if(pos==0)
{
ptr=start;
start=start->next ;
printf("nThe deleted element is:%dt",ptr->info );
free(ptr);
}
else
{
ptr=start;
for(i=0;i<pos;i++) { temp=ptr; ptr=ptr->next ;
if(ptr==NULL)
{
printf("nPosition not Found:n");
return;
}
}
temp->next =ptr->next ;
printf("nThe deleted element is:%dt",ptr->info );
free(ptr);
}
}
}

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