對於單鏈表的基本操作有 初始化,銷燬,以及頭部插入,尾部插入,頭部刪除,尾部刪除以及計算單鏈表的長度。
我這裏的初始化函數,因爲有一個鏈表頭,所以malloc的時候,是從第二個空間進行空間開闢的。並且在釋放的時候,也是從第二個空間開始釋放的。並且頭部的插入和刪除,也都是第二個位置的刪除與插入,如果需要修改頭的值,就需要調用另外一個函數。這個我會在別的博客裏面寫清楚。
具體實現並不難,咋們直接看代碼,有的關鍵點我會在代碼裏備註出來(如果沒有就不備註了,不難理解)
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
typedef struct List
{
int date;
struct List * next;
}List;
void init_list(List *ls)
{
List *tmp = ls;
int i = 0;
for (i = 0; i < 10; i++)
{
ls->date = i;
ls->next = (List*)malloc(sizeof(List));
ls = ls->next;
}
ls->date = i;
ls->next = NULL;
}
void push_front(List *ls,int date)
{
List * tmp = (List *)malloc(sizeof(List));
tmp->date = date;
tmp->next = ls->next;
ls->next = tmp;
}
void pop_front(List *ls)
{
List *tmp = ls->next;
ls->next = ls->next->next;
free(tmp);
}
void push_back(List *ls, int date)
{
while (ls->next)
{
ls = ls->next;
}
ls->next = (List *)malloc(sizeof(List));
ls->next->date = date;
ls->next->next = NULL;
}
void pop_back(List *ls)
{
while (ls->next->next)
{
ls = ls->next;
}
free(ls->next);
ls->next = NULL;
}
void print_list(List *ls)
{
int i = 0;
for ( i = 0; ls->next; i++)
{
printf("%d\n", ls->date);
ls = ls->next;
}
putchar('\n');
printf("%d\n", ls->date);
}
void free_list(List *ls)
{
List *tmp;
ls = ls->next;
for (int i = 0; ls->next;i++)
{
tmp = ls->next;
free(ls);
ls = tmp;
}
free(ls);
}
int length(List *ls)
{
int num = 1;
while (ls->next)
{
num++;
ls = ls->next;
}
return num;
}
int main()//這個是測試代碼,裏面的一些東西都是爲了測試整個代碼的正確性的,可以自己寫這個
{
List ls;
int i = 13;
init_list(&ls);
printf("%d\n", length(&ls));
push_front(&ls, i);
printf("%d\n", length(&ls));
pop_front(&ls);
push_back(&ls, 20);
printf("%d\n", length(&ls));
pop_back(&ls);
print_list(&ls);
free_list(&ls);
return 0;
}