diff --git a/Chapter11/ds/line/list/linklist/double/kernel/list.h b/Chapter11/ds/line/list/linklist/double/kernel/list.h
new file mode 100644
index 0000000..1d87fe2
--- /dev/null
+++ b/Chapter11/ds/line/list/linklist/double/kernel/list.h
@@ -0,0 +1,56 @@
+#ifndef LINUX_LIST_H__
+#define LINUX_LIST_H__
+
+struct list_head
+{
+    struct list_head *prev;
+    struct list_head *next;
+};
+
+#define LIST_HEAD_INIT(name) \
+    {                        \
+        &(name), &(name)     \
+    }
+
+#define LIST_HEAD(name) struct list_head name = LIST_HEAD_INIT(name)
+
+static inline void __list_add(struct list_head *new,
+                              struct list_head *prev,
+                              struct list_head *next)
+{
+    next->prev = new;
+    new->next  = next;
+    new->prev  = prev;
+    prev->next = new;
+}
+
+static inline void list_add(struct list_head *new, struct list_head *head)
+{
+    __list_add(new, head, head->next);
+}
+
+#define __list_for_each(pos, head) \
+    for (pos = (head)->next; pos != (head); pos = pos->next)
+
+
+// 这个内核的链表仅包含两个指针，用来被数据包含
+// 希望由嵌入的指针找回到完整的结构体
+
+/**
+ * ptr->cur
+ * type->struct score_st
+ * member->node
+ *
+ */
+
+#define offsetof(TYPE, MEMBER) ((size_t) & ((TYPE *)0)->MEMBER)
+
+#define container_of(ptr, type, member)                    \
+    ({                                                     \
+        const typeof(((type *)0)->member) *__mptr = (ptr); \
+        (type *)((char *)__mptr - offsetof(type, member)); \
+    })
+
+#define list_entry(ptr, type, member) container_of(ptr, type, member)
+
+#endif
\ No newline at end of file
diff --git a/Chapter11/ds/line/list/linklist/double/kernel/main.c b/Chapter11/ds/line/list/linklist/double/kernel/main.c
new file mode 100644
index 0000000..77bfb7a
--- /dev/null
+++ b/Chapter11/ds/line/list/linklist/double/kernel/main.c
@@ -0,0 +1,63 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "list.h"
+
+#define NAMESIZE 32
+
+struct score_st
+{
+    int              id;
+    char             name[NAMESIZE];
+    struct list_head node;
+    int              math;
+    int              chinese;
+};
+
+static void print_s(struct score_st *d)
+{
+    printf("%d %s %d %d \n", d->id, d->name, d->math, d->chinese);
+}
+
+int main()
+{
+    int               i;
+    struct score_st  *datap;
+    struct list_head *cur;
+
+    LIST_HEAD(head);
+
+    for (i = 0; i < 7; i++)
+    {
+        datap = malloc(sizeof(*datap));
+        if (NULL == datap)
+            exit(1);
+
+        datap->id = i;
+        snprintf(datap->name, NAMESIZE, "stu%d", i);
+        datap->math    = rand() % 100;
+        datap->chinese = rand() % 100;
+
+        list_add(&datap->node, &head);
+    }
+
+    __list_for_each(cur, &head)
+    {
+        datap = list_entry(cur, struct score_st, node);
+        print_s(datap);
+    }
+
+
+    __list_for_each(cur, &head)
+    {
+        datap = list_entry(cur, struct score_st, node);
+        if (5 == datap->id)
+            break;
+    }
+    if (cur == &head)
+        printf("Can not find!\n");
+    else
+        print_s(datap);
+
+    exit(0);
+}
\ No newline at end of file
diff --git a/Chapter11/ds/line/list/linklist/double/kernel/makefile b/Chapter11/ds/line/list/linklist/double/kernel/makefile
new file mode 100644
index 0000000..a7681ed
--- /dev/null
+++ b/Chapter11/ds/line/list/linklist/double/kernel/makefile
@@ -0,0 +1,31 @@
+# 方便起见一般都会先定义编译器链接器
+CC = gcc 
+LD = gcc
+
+# 正则表达式表示目录下所有.c文件，相当于：SRCS = main.c a.c b.c
+SRCS = $(wildcard *.c)
+
+# OBJS表示SRCS中把列表中的.c全部替换为.o，相当于：OBJS = main.o a.o b.o
+OBJS = $(patsubst %c, %o, $(SRCS))
+
+# 可执行文件的名字
+TARGET = main
+
+# .PHONE伪目标，具体含义百度一下一大堆介绍
+.PHONY:all clean
+
+# 要生成的目标文件
+all: $(TARGET)
+
+# 第一行依赖关系：冒号后面为依赖的文件，相当于Hello: main.o a.o b.o
+# 第二行规则：$@表示目标文件，$^表示所有依赖文件，$<表示第一个依赖文件
+$(TARGET): $(OBJS)
+	$(LD) -o $@ $^
+
+# 上一句目标文件依赖一大堆.o文件，这句表示所有.o都由相应名字的.c文件自动生成
+%.o:%.c
+	$(CC) -c $^
+
+# make clean删除所有.o和目标文件
+clean:
+	rm -f $(OBJS) $(TARGET)
diff --git a/Chapter11/ds/line/list/linklist/double/lib1/Makefile b/Chapter11/ds/line/list/linklist/double/lib1/Makefile
new file mode 100644
index 0000000..a7681ed
--- /dev/null
+++ b/Chapter11/ds/line/list/linklist/double/lib1/Makefile
@@ -0,0 +1,31 @@
+# 方便起见一般都会先定义编译器链接器
+CC = gcc 
+LD = gcc
+
+# 正则表达式表示目录下所有.c文件，相当于：SRCS = main.c a.c b.c
+SRCS = $(wildcard *.c)
+
+# OBJS表示SRCS中把列表中的.c全部替换为.o，相当于：OBJS = main.o a.o b.o
+OBJS = $(patsubst %c, %o, $(SRCS))
+
+# 可执行文件的名字
+TARGET = main
+
+# .PHONE伪目标，具体含义百度一下一大堆介绍
+.PHONY:all clean
+
+# 要生成的目标文件
+all: $(TARGET)
+
+# 第一行依赖关系：冒号后面为依赖的文件，相当于Hello: main.o a.o b.o
+# 第二行规则：$@表示目标文件，$^表示所有依赖文件，$<表示第一个依赖文件
+$(TARGET): $(OBJS)
+	$(LD) -o $@ $^
+
+# 上一句目标文件依赖一大堆.o文件，这句表示所有.o都由相应名字的.c文件自动生成
+%.o:%.c
+	$(CC) -c $^
+
+# make clean删除所有.o和目标文件
+clean:
+	rm -f $(OBJS) $(TARGET)
diff --git a/Chapter11/ds/line/list/linklist/double/lib1/llist.c b/Chapter11/ds/line/list/linklist/double/lib1/llist.c
new file mode 100644
index 0000000..2ec3aed
--- /dev/null
+++ b/Chapter11/ds/line/list/linklist/double/lib1/llist.c
@@ -0,0 +1,134 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "llist.h"
+
+LLIST *llist_create(int initsize)
+{
+    LLIST *new;
+
+    new = malloc(sizeof(*new));   // !!! 不是sizeof(initsize),也不是new,是*new
+    if (NULL == new)
+        return NULL;
+
+    new->size      = initsize;
+    new->head.data = NULL;
+    new->head.prev = &new->head;
+    new->head.next = &new->head;
+
+    return new;
+}
+
+int llist_insert(LLIST *ptr, const void *data, int mode)
+{
+    struct llist_node_st *newnode;
+
+    newnode = malloc(sizeof(*newnode));
+    if (NULL == newnode)
+        return -1;
+
+    newnode->data = malloc(ptr->size);
+    if (newnode->data == NULL)
+        return -2;
+
+    memcpy(newnode->data, data, ptr->size);
+
+    if (LLIST_FORWARD == mode)
+    {
+        newnode->prev = &ptr->head;
+        newnode->next = ptr->head.next;
+    }
+    else if (LLIST_BACKWARD == mode)
+    {
+        newnode->prev = ptr->head.prev;
+        newnode->next = &ptr->head;
+    }
+    else   // error
+    {
+        return -3;
+    }
+
+    // !!! 妙啊
+    newnode->next->prev = newnode;
+    newnode->prev->next = newnode;
+
+    return 0;
+}
+
+static struct llist_node_st *find_(LLIST *ptr, const void *key, llist_cmp *cmp)
+{
+    struct llist_node_st *cur;
+
+    for (cur = ptr->head.next; cur != &ptr->head; cur = cur->next)
+    {
+        if (0 == cmp(key, cur->data))
+            break;
+    }
+
+    return cur;   // 找不到的时候，返回的cur就是ptr，返回NULL
+}
+
+void *llist_find(LLIST *ptr, const void *key, llist_cmp *cmp)
+{
+    return find_(ptr, key, cmp)->data;
+}
+
+int llist_delete(LLIST *ptr, const void *key, llist_cmp *cmp)
+{
+    struct llist_node_st *node;
+
+    node = find_(ptr, key, cmp);
+    if (node == &ptr->head)
+        return -1;
+
+    // !!!
+    node->prev->next = node->next;
+    node->next->prev = node->prev;
+    free(node->data);
+    free(node);
+
+    return 0;
+}
+
+int llist_fetch(LLIST *ptr, const void *key, llist_cmp *cmp, void *data)
+{
+    struct llist_node_st *node;
+
+    node = find_(ptr, key, cmp);
+    if (node == &ptr->head)
+        return -1;
+
+    node->next->prev = node->prev;
+    node->prev->next = node->next;
+
+    if (data != NULL)
+        memcpy(data, node->data, ptr->size);
+
+    free(node->data);
+    free(node);
+
+    return 0;
+}
+
+void llist_travel(LLIST *ptr, llist_op *op)
+{
+    struct llist_node_st *cur;
+
+    for (cur = ptr->head.next; cur != &ptr->head; cur = cur->next)
+        op(cur->data);
+}
+
+void llist_destroy(LLIST *ptr)
+{
+    struct llist_node_st *cur, *next;
+
+    for (cur = ptr->head.next; cur != &ptr->head; cur = next)
+    {
+        next = cur->next;
+        free(cur->data);
+        free(cur);
+    }
+
+    free(ptr);
+}
diff --git a/Chapter11/ds/line/list/linklist/double/lib1/llist.h b/Chapter11/ds/line/list/linklist/double/lib1/llist.h
new file mode 100644
index 0000000..25178a9
--- /dev/null
+++ b/Chapter11/ds/line/list/linklist/double/lib1/llist.h
@@ -0,0 +1,37 @@
+#ifndef LLIST_H__
+#define LLIST_H__
+
+#define LLIST_FORWARD  1
+#define LLIST_BACKWARD 2
+
+struct llist_node_st
+{
+    void                 *data;
+    struct llist_node_st *prev;
+    struct llist_node_st *next;
+};
+
+typedef struct
+{
+    int                  size;
+    struct llist_node_st head;
+} LLIST;
+
+typedef void llist_op(const void *);
+typedef int  llist_cmp(const void *, const void *);
+
+LLIST *llist_create(int initsize);
+
+int llist_insert(LLIST *ptr, const void *data, int mode);
+
+void *llist_find(LLIST *ptr, const void *key, llist_cmp *);
+
+int llist_delete(LLIST *, const void *key, llist_cmp *);
+
+int llist_fetch(LLIST *, const void *key, llist_cmp *, void *data);
+
+void llist_travel(LLIST *ptr, llist_op *op);
+
+void llist_destroy(LLIST *ptr);
+
+#endif
diff --git a/Chapter11/ds/line/list/linklist/double/lib1/main.c b/Chapter11/ds/line/list/linklist/double/lib1/main.c
new file mode 100644
index 0000000..e736037
--- /dev/null
+++ b/Chapter11/ds/line/list/linklist/double/lib1/main.c
@@ -0,0 +1,95 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "llist.h"
+
+#define NAMESIZE 32
+
+struct score_st
+{
+    int  id;
+    char name[NAMESIZE];
+    int  math;
+    int  chinese;
+};
+
+void print_s(const void *record)
+{
+    const struct score_st *r = record;
+
+    printf("%d %s %d %d\n", r->id, r->name, r->math, r->chinese);
+}
+
+int id_cmp(const void *key, const void *record)
+{
+    const int             *k = key;
+    const struct score_st *r = record;
+
+    return (*k - r->id);
+}
+
+int name_cmp(const void *key, const void *record)
+{
+    const char            *k = key;
+    const struct score_st *r = record;
+
+    return strcmp(k, r->name);
+}
+
+
+int main()
+{
+    LLIST          *handler;
+    int             i, ret;
+    struct score_st tmp;
+
+    handler = llist_create(sizeof(struct score_st));
+    if (NULL == handler)
+        exit(1);
+
+    for (i = 0; i < 7; i++)
+    {
+        tmp.id = i;
+        snprintf(tmp.name, NAMESIZE, "std%d", i);
+        tmp.math    = rand() % 100;
+        tmp.chinese = rand() % 100;
+
+        ret = llist_insert(handler, &tmp, LLIST_FORWARD);
+        if (ret)
+            exit(1);
+    }
+
+    llist_travel(handler, print_s);
+
+    printf("\n\n");
+
+    // int id = 3;
+    char *del_name = "std6";
+
+    // ret = llist_delete(handler, &id, id_cmp);
+    ret = llist_delete(handler, del_name, name_cmp);
+    if (ret)
+        printf("llist_deleter failed!\n");
+
+    llist_travel(handler, print_s);
+
+
+
+#if 0
+    int              id = 3;
+    struct score_st *data;
+
+    data = llist_find(handler, &id, id_cmp);
+    if (NULL == data)
+        printf("Can not find!\n");
+    else
+        print_s(data);
+
+#endif
+
+
+    llist_destroy(handler);
+
+    exit(0);
+}
\ No newline at end of file
diff --git a/Chapter11/ds/line/list/linklist/double/lib2/Makefile b/Chapter11/ds/line/list/linklist/double/lib2/Makefile
new file mode 100644
index 0000000..a7681ed
--- /dev/null
+++ b/Chapter11/ds/line/list/linklist/double/lib2/Makefile
@@ -0,0 +1,31 @@
+# 方便起见一般都会先定义编译器链接器
+CC = gcc 
+LD = gcc
+
+# 正则表达式表示目录下所有.c文件，相当于：SRCS = main.c a.c b.c
+SRCS = $(wildcard *.c)
+
+# OBJS表示SRCS中把列表中的.c全部替换为.o，相当于：OBJS = main.o a.o b.o
+OBJS = $(patsubst %c, %o, $(SRCS))
+
+# 可执行文件的名字
+TARGET = main
+
+# .PHONE伪目标，具体含义百度一下一大堆介绍
+.PHONY:all clean
+
+# 要生成的目标文件
+all: $(TARGET)
+
+# 第一行依赖关系：冒号后面为依赖的文件，相当于Hello: main.o a.o b.o
+# 第二行规则：$@表示目标文件，$^表示所有依赖文件，$<表示第一个依赖文件
+$(TARGET): $(OBJS)
+	$(LD) -o $@ $^
+
+# 上一句目标文件依赖一大堆.o文件，这句表示所有.o都由相应名字的.c文件自动生成
+%.o:%.c
+	$(CC) -c $^
+
+# make clean删除所有.o和目标文件
+clean:
+	rm -f $(OBJS) $(TARGET)
diff --git a/Chapter11/ds/line/list/linklist/double/lib2/llist.c b/Chapter11/ds/line/list/linklist/double/lib2/llist.c
new file mode 100644
index 0000000..1190181
--- /dev/null
+++ b/Chapter11/ds/line/list/linklist/double/lib2/llist.c
@@ -0,0 +1,130 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "llist.h"
+
+LLIST *llist_create(int initsize)
+{
+    LLIST *new;
+
+    new = malloc(sizeof(*new));   // !!! 不是sizeof(initsize),也不是new,是*new
+    if (NULL == new)
+        return NULL;
+
+    new->size      = initsize;
+    new->head.prev = &new->head;
+    new->head.next = &new->head;
+
+    return new;
+}
+
+int llist_insert(LLIST *ptr, const void *data, int mode)
+{
+    struct llist_node_st *newnode;
+
+    newnode = malloc(sizeof(*newnode) + ptr->size);   // -4
+    if (NULL == newnode)
+        return -1;
+
+    memcpy(newnode->data, data, ptr->size);
+
+    if (LLIST_FORWARD == mode)
+    {
+        newnode->prev = &ptr->head;
+        newnode->next = ptr->head.next;
+    }
+    else if (LLIST_BACKWARD == mode)
+    {
+        newnode->prev = ptr->head.prev;
+        newnode->next = &ptr->head;
+    }
+    else   // error
+    {
+        return -3;
+    }
+
+    // !!! 妙啊
+    newnode->next->prev = newnode;
+    newnode->prev->next = newnode;
+
+    return 0;
+}
+
+static struct llist_node_st *find_(LLIST *ptr, const void *key, llist_cmp *cmp)
+{
+    struct llist_node_st *cur;
+
+    for (cur = ptr->head.next; cur != &ptr->head; cur = cur->next)
+    {
+        if (0 == cmp(key, cur->data))
+            break;
+    }
+
+    return cur;   // 找不到的时候，返回的cur就是ptr，返回NULL
+}
+
+void *llist_find(LLIST *ptr, const void *key, llist_cmp *cmp)
+{
+    struct llist_node_st *node;
+    node = find_(ptr, key, cmp);
+    if (node == &ptr->head)
+        return NULL;
+
+    return node->data;
+}
+
+int llist_delete(LLIST *ptr, const void *key, llist_cmp *cmp)
+{
+    struct llist_node_st *node;
+
+    node = find_(ptr, key, cmp);
+    if (node == &ptr->head)
+        return -1;
+
+    // !!!
+    node->prev->next = node->next;
+    node->next->prev = node->prev;
+    free(node);
+    return 0;
+}
+
+int llist_fetch(LLIST *ptr, const void *key, llist_cmp *cmp, void *data)
+{
+    struct llist_node_st *node;
+
+    node = find_(ptr, key, cmp);
+    if (node == &ptr->head)
+        return -1;
+
+    node->next->prev = node->prev;
+    node->prev->next = node->next;
+
+    if (data != NULL)
+        memcpy(data, node->data, ptr->size);
+
+    free(node);
+
+    return 0;
+}
+
+void llist_travel(LLIST *ptr, llist_op *op)
+{
+    struct llist_node_st *cur;
+
+    for (cur = ptr->head.next; cur != &ptr->head; cur = cur->next)
+        op(cur->data);
+}
+
+void llist_destroy(LLIST *ptr)
+{
+    struct llist_node_st *cur, *next;
+
+    for (cur = ptr->head.next; cur != &ptr->head; cur = next)
+    {
+        next = cur->next;
+        free(cur);
+    }
+
+    free(ptr);
+}
diff --git a/Chapter11/ds/line/list/linklist/double/lib2/llist.h b/Chapter11/ds/line/list/linklist/double/lib2/llist.h
new file mode 100644
index 0000000..48457e4
--- /dev/null
+++ b/Chapter11/ds/line/list/linklist/double/lib2/llist.h
@@ -0,0 +1,39 @@
+#ifndef LLIST_H__
+#define LLIST_H__
+
+#define LLIST_FORWARD  1
+#define LLIST_BACKWARD 2
+
+// !!! 变长结构体
+struct llist_node_st
+{
+    struct llist_node_st *prev;
+    struct llist_node_st *next;
+    // data要放在最后
+    char data[1];   // 占位符，数据的起始。C99才只是[0]
+};
+
+typedef struct
+{
+    int                  size;
+    struct llist_node_st head;
+} LLIST;
+
+typedef void llist_op(const void *);
+typedef int  llist_cmp(const void *, const void *);
+
+LLIST *llist_create(int initsize);
+
+int llist_insert(LLIST *ptr, const void *data, int mode);
+
+void *llist_find(LLIST *ptr, const void *key, llist_cmp *);
+
+int llist_delete(LLIST *, const void *key, llist_cmp *);
+
+int llist_fetch(LLIST *, const void *key, llist_cmp *, void *data);
+
+void llist_travel(LLIST *ptr, llist_op *op);
+
+void llist_destroy(LLIST *ptr);
+
+#endif
diff --git a/Chapter11/ds/line/list/linklist/double/lib2/main.c b/Chapter11/ds/line/list/linklist/double/lib2/main.c
new file mode 100644
index 0000000..e736037
--- /dev/null
+++ b/Chapter11/ds/line/list/linklist/double/lib2/main.c
@@ -0,0 +1,95 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "llist.h"
+
+#define NAMESIZE 32
+
+struct score_st
+{
+    int  id;
+    char name[NAMESIZE];
+    int  math;
+    int  chinese;
+};
+
+void print_s(const void *record)
+{
+    const struct score_st *r = record;
+
+    printf("%d %s %d %d\n", r->id, r->name, r->math, r->chinese);
+}
+
+int id_cmp(const void *key, const void *record)
+{
+    const int             *k = key;
+    const struct score_st *r = record;
+
+    return (*k - r->id);
+}
+
+int name_cmp(const void *key, const void *record)
+{
+    const char            *k = key;
+    const struct score_st *r = record;
+
+    return strcmp(k, r->name);
+}
+
+
+int main()
+{
+    LLIST          *handler;
+    int             i, ret;
+    struct score_st tmp;
+
+    handler = llist_create(sizeof(struct score_st));
+    if (NULL == handler)
+        exit(1);
+
+    for (i = 0; i < 7; i++)
+    {
+        tmp.id = i;
+        snprintf(tmp.name, NAMESIZE, "std%d", i);
+        tmp.math    = rand() % 100;
+        tmp.chinese = rand() % 100;
+
+        ret = llist_insert(handler, &tmp, LLIST_FORWARD);
+        if (ret)
+            exit(1);
+    }
+
+    llist_travel(handler, print_s);
+
+    printf("\n\n");
+
+    // int id = 3;
+    char *del_name = "std6";
+
+    // ret = llist_delete(handler, &id, id_cmp);
+    ret = llist_delete(handler, del_name, name_cmp);
+    if (ret)
+        printf("llist_deleter failed!\n");
+
+    llist_travel(handler, print_s);
+
+
+
+#if 0
+    int              id = 3;
+    struct score_st *data;
+
+    data = llist_find(handler, &id, id_cmp);
+    if (NULL == data)
+        printf("Can not find!\n");
+    else
+        print_s(data);
+
+#endif
+
+
+    llist_destroy(handler);
+
+    exit(0);
+}
\ No newline at end of file
diff --git a/Chapter11/ds/line/list/linklist/double/lib3/Makefile b/Chapter11/ds/line/list/linklist/double/lib3/Makefile
new file mode 100644
index 0000000..a7681ed
--- /dev/null
+++ b/Chapter11/ds/line/list/linklist/double/lib3/Makefile
@@ -0,0 +1,31 @@
+# 方便起见一般都会先定义编译器链接器
+CC = gcc 
+LD = gcc
+
+# 正则表达式表示目录下所有.c文件，相当于：SRCS = main.c a.c b.c
+SRCS = $(wildcard *.c)
+
+# OBJS表示SRCS中把列表中的.c全部替换为.o，相当于：OBJS = main.o a.o b.o
+OBJS = $(patsubst %c, %o, $(SRCS))
+
+# 可执行文件的名字
+TARGET = main
+
+# .PHONE伪目标，具体含义百度一下一大堆介绍
+.PHONY:all clean
+
+# 要生成的目标文件
+all: $(TARGET)
+
+# 第一行依赖关系：冒号后面为依赖的文件，相当于Hello: main.o a.o b.o
+# 第二行规则：$@表示目标文件，$^表示所有依赖文件，$<表示第一个依赖文件
+$(TARGET): $(OBJS)
+	$(LD) -o $@ $^
+
+# 上一句目标文件依赖一大堆.o文件，这句表示所有.o都由相应名字的.c文件自动生成
+%.o:%.c
+	$(CC) -c $^
+
+# make clean删除所有.o和目标文件
+clean:
+	rm -f $(OBJS) $(TARGET)
diff --git a/Chapter11/ds/line/list/linklist/double/lib3/llist.c b/Chapter11/ds/line/list/linklist/double/lib3/llist.c
new file mode 100644
index 0000000..d7b087d
--- /dev/null
+++ b/Chapter11/ds/line/list/linklist/double/lib3/llist.c
@@ -0,0 +1,142 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "llist.h"
+
+int   llist_insert(LLIST *ptr, const void *data, int mode);
+void *llist_find(LLIST *ptr, const void *key, llist_cmp *);
+int   llist_delete(LLIST *, const void *key, llist_cmp *);
+int   llist_fetch(LLIST *, const void *key, llist_cmp *, void *data);
+void  llist_travel(LLIST *ptr, llist_op *op);
+
+LLIST *llist_create(int initsize)
+{
+    LLIST *new;
+
+    new = malloc(sizeof(*new));   // !!! 不是sizeof(initsize),也不是new,是*new
+    if (NULL == new)
+        return NULL;
+
+    new->size      = initsize;
+    new->head.prev = &new->head;
+    new->head.next = &new->head;
+
+    new->insert = llist_insert;
+    new->delete = llist_delete;
+    new->find   = llist_find;
+    new->fetch  = llist_fetch;
+    new->travel = llist_travel;
+
+    return new;
+}
+
+int llist_insert(LLIST *ptr, const void *data, int mode)
+{
+    struct llist_node_st *newnode;
+
+    newnode = malloc(sizeof(*newnode) + ptr->size);   // -4
+    if (NULL == newnode)
+        return -1;
+
+    memcpy(newnode->data, data, ptr->size);
+
+    if (LLIST_FORWARD == mode)
+    {
+        newnode->prev = &ptr->head;
+        newnode->next = ptr->head.next;
+    }
+    else if (LLIST_BACKWARD == mode)
+    {
+        newnode->prev = ptr->head.prev;
+        newnode->next = &ptr->head;
+    }
+    else   // error
+    {
+        return -3;
+    }
+
+    // !!! 妙啊
+    newnode->next->prev = newnode;
+    newnode->prev->next = newnode;
+
+    return 0;
+}
+
+static struct llist_node_st *find_(LLIST *ptr, const void *key, llist_cmp *cmp)
+{
+    struct llist_node_st *cur;
+
+    for (cur = ptr->head.next; cur != &ptr->head; cur = cur->next)
+    {
+        if (0 == cmp(key, cur->data))
+            break;
+    }
+
+    return cur;   // 找不到的时候，返回的cur就是ptr，返回NULL
+}
+
+void *llist_find(LLIST *ptr, const void *key, llist_cmp *cmp)
+{
+    struct llist_node_st *node;
+    node = find_(ptr, key, cmp);
+    if (node == &ptr->head)
+        return NULL;
+
+    return node->data;
+}
+
+int llist_delete(LLIST *ptr, const void *key, llist_cmp *cmp)
+{
+    struct llist_node_st *node;
+
+    node = find_(ptr, key, cmp);
+    if (node == &ptr->head)
+        return -1;
+
+    // !!!
+    node->prev->next = node->next;
+    node->next->prev = node->prev;
+    free(node);
+    return 0;
+}
+
+int llist_fetch(LLIST *ptr, const void *key, llist_cmp *cmp, void *data)
+{
+    struct llist_node_st *node;
+
+    node = find_(ptr, key, cmp);
+    if (node == &ptr->head)
+        return -1;
+
+    node->next->prev = node->prev;
+    node->prev->next = node->next;
+
+    if (data != NULL)
+        memcpy(data, node->data, ptr->size);
+
+    free(node);
+
+    return 0;
+}
+
+void llist_travel(LLIST *ptr, llist_op *op)
+{
+    struct llist_node_st *cur;
+
+    for (cur = ptr->head.next; cur != &ptr->head; cur = cur->next)
+        op(cur->data);
+}
+
+void llist_destroy(LLIST *ptr)
+{
+    struct llist_node_st *cur, *next;
+
+    for (cur = ptr->head.next; cur != &ptr->head; cur = next)
+    {
+        next = cur->next;
+        free(cur);
+    }
+
+    free(ptr);
+}
diff --git a/Chapter11/ds/line/list/linklist/double/lib3/llist.h b/Chapter11/ds/line/list/linklist/double/lib3/llist.h
new file mode 100644
index 0000000..2abdfb4
--- /dev/null
+++ b/Chapter11/ds/line/list/linklist/double/lib3/llist.h
@@ -0,0 +1,38 @@
+#ifndef LLIST_H__
+#define LLIST_H__
+
+#define LLIST_FORWARD  1
+#define LLIST_BACKWARD 2
+
+typedef void llist_op(const void *);
+typedef int  llist_cmp(const void *, const void *);
+
+// !!! 变长结构体
+struct llist_node_st
+{
+    struct llist_node_st *prev;
+    struct llist_node_st *next;
+    // data要放在最后
+    char data[1];   // 占位符，数据的起始。C99才只是[0]
+};
+
+typedef struct llist_head
+{
+    int                  size;
+    struct llist_node_st head;
+
+    int (*insert)(struct llist_head *, const void *, int);
+    void *(*find)(struct llist_head *, const void *, llist_cmp *);
+    int (*delete)(struct llist_head *, const void *, llist_cmp *);
+    int (*fetch)(struct llist_head *, const void *, llist_cmp *, void *);
+    void (*travel)(struct llist_head *, llist_op *);
+
+} LLIST;
+
+
+
+LLIST *llist_create(int initsize);
+
+void llist_destroy(LLIST *ptr);
+
+#endif
diff --git a/Chapter11/ds/line/list/linklist/double/lib3/main.c b/Chapter11/ds/line/list/linklist/double/lib3/main.c
new file mode 100644
index 0000000..028341c
--- /dev/null
+++ b/Chapter11/ds/line/list/linklist/double/lib3/main.c
@@ -0,0 +1,97 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "llist.h"
+
+#define NAMESIZE 32
+
+struct score_st
+{
+    int  id;
+    char name[NAMESIZE];
+    int  math;
+    int  chinese;
+};
+
+void print_s(const void *record)
+{
+    const struct score_st *r = record;
+
+    printf("%d %s %d %d\n", r->id, r->name, r->math, r->chinese);
+}
+
+int id_cmp(const void *key, const void *record)
+{
+    const int             *k = key;
+    const struct score_st *r = record;
+
+    return (*k - r->id);
+}
+
+int name_cmp(const void *key, const void *record)
+{
+    const char            *k = key;
+    const struct score_st *r = record;
+
+    return strcmp(k, r->name);
+}
+
+
+int main()
+{
+    LLIST          *handler;
+    int             i, ret;
+    struct score_st tmp;
+
+    handler = llist_create(sizeof(struct score_st));
+    if (NULL == handler)
+        exit(1);
+
+    for (i = 0; i < 7; i++)
+    {
+        tmp.id = i;
+        snprintf(tmp.name, NAMESIZE, "std%d", i);
+        tmp.math    = rand() % 100;
+        tmp.chinese = rand() % 100;
+
+        ret = handler->insert(handler, &tmp, LLIST_FORWARD);
+        if (ret)
+            exit(1);
+    }
+
+    handler->travel(handler, print_s);
+
+
+
+#if 0
+    printf("\n\n");
+
+    // int id = 3;
+    char *del_name = "std6";
+
+    // ret = llist_delete(handler, &id, id_cmp);
+    ret = llist_delete(handler, del_name, name_cmp);
+    if (ret)
+        printf("llist_deleter failed!\n");
+
+    llist_travel(handler, print_s);
+
+
+
+    int              id = 3;
+    struct score_st *data;
+
+    data = llist_find(handler, &id, id_cmp);
+    if (NULL == data)
+        printf("Can not find!\n");
+    else
+        print_s(data);
+
+#endif
+
+
+    llist_destroy(handler);
+
+    exit(0);
+}
\ No newline at end of file
diff --git a/Chapter11/ds/line/list/linklist/double/lib4/Makefile b/Chapter11/ds/line/list/linklist/double/lib4/Makefile
new file mode 100644
index 0000000..a7681ed
--- /dev/null
+++ b/Chapter11/ds/line/list/linklist/double/lib4/Makefile
@@ -0,0 +1,31 @@
+# 方便起见一般都会先定义编译器链接器
+CC = gcc 
+LD = gcc
+
+# 正则表达式表示目录下所有.c文件，相当于：SRCS = main.c a.c b.c
+SRCS = $(wildcard *.c)
+
+# OBJS表示SRCS中把列表中的.c全部替换为.o，相当于：OBJS = main.o a.o b.o
+OBJS = $(patsubst %c, %o, $(SRCS))
+
+# 可执行文件的名字
+TARGET = main
+
+# .PHONE伪目标，具体含义百度一下一大堆介绍
+.PHONY:all clean
+
+# 要生成的目标文件
+all: $(TARGET)
+
+# 第一行依赖关系：冒号后面为依赖的文件，相当于Hello: main.o a.o b.o
+# 第二行规则：$@表示目标文件，$^表示所有依赖文件，$<表示第一个依赖文件
+$(TARGET): $(OBJS)
+	$(LD) -o $@ $^
+
+# 上一句目标文件依赖一大堆.o文件，这句表示所有.o都由相应名字的.c文件自动生成
+%.o:%.c
+	$(CC) -c $^
+
+# make clean删除所有.o和目标文件
+clean:
+	rm -f $(OBJS) $(TARGET)
diff --git a/Chapter11/ds/line/list/linklist/double/lib4/llist.c b/Chapter11/ds/line/list/linklist/double/lib4/llist.c
new file mode 100644
index 0000000..014853c
--- /dev/null
+++ b/Chapter11/ds/line/list/linklist/double/lib4/llist.c
@@ -0,0 +1,153 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "llist.h"
+
+// !!! 变长结构体
+struct llist_node_st
+{
+    struct llist_node_st *prev;
+    struct llist_node_st *next;
+    // data要放在最后
+    char data[1];   // 占位符，数据的起始。C99才只是[0]
+};
+
+struct llist_head_st
+{
+    int                  size;
+    struct llist_node_st head;
+};
+
+LLIST *llist_create(int initsize)
+{
+    struct llist_head_st *new;
+
+    new = malloc(sizeof(*new));   // !!! 不是sizeof(initsize),也不是new,是*new
+    if (NULL == new)
+        return NULL;
+
+    new->size      = initsize;
+    new->head.prev = &new->head;
+    new->head.next = &new->head;
+
+    return new;
+}
+
+int llist_insert(LLIST *p, const void *data, int mode)
+{
+    struct llist_node_st *newnode;
+    struct llist_head_st *ptr = p;
+
+    newnode = malloc(sizeof(*newnode) + ptr->size);   // -4
+    if (NULL == newnode)
+        return -1;
+
+    memcpy(newnode->data, data, ptr->size);
+
+    if (LLIST_FORWARD == mode)
+    {
+        newnode->prev = &ptr->head;
+        newnode->next = ptr->head.next;
+    }
+    else if (LLIST_BACKWARD == mode)
+    {
+        newnode->prev = ptr->head.prev;
+        newnode->next = &ptr->head;
+    }
+    else   // error
+    {
+        return -3;
+    }
+
+    // !!! 妙啊
+    newnode->next->prev = newnode;
+    newnode->prev->next = newnode;
+
+    return 0;
+}
+
+static struct llist_node_st *find_(struct llist_head_st *ptr,
+                                   const void           *key,
+                                   llist_cmp            *cmp)
+{
+    struct llist_node_st *cur;
+
+    for (cur = ptr->head.next; cur != &ptr->head; cur = cur->next)
+    {
+        if (0 == cmp(key, cur->data))
+            break;
+    }
+
+    return cur;   // 找不到的时候，返回的cur就是ptr，返回NULL
+}
+
+void *llist_find(LLIST *p, const void *key, llist_cmp *cmp)
+{
+    struct llist_head_st *ptr = p;
+    struct llist_node_st *node;
+    node = find_(ptr, key, cmp);
+    if (node == &ptr->head)
+        return NULL;
+
+    return node->data;
+}
+
+int llist_delete(LLIST *p, const void *key, llist_cmp *cmp)
+{
+    struct llist_head_st *ptr = p;
+    struct llist_node_st *node;
+
+    node = find_(ptr, key, cmp);
+    if (node == &ptr->head)
+        return -1;
+
+    // !!!
+    node->prev->next = node->next;
+    node->next->prev = node->prev;
+    free(node);
+    return 0;
+}
+
+int llist_fetch(LLIST *p, const void *key, llist_cmp *cmp, void *data)
+{
+    struct llist_head_st *ptr = p;
+    struct llist_node_st *node;
+
+    node = find_(ptr, key, cmp);
+    if (node == &ptr->head)
+        return -1;
+
+    node->next->prev = node->prev;
+    node->prev->next = node->next;
+
+    if (data != NULL)
+        memcpy(data, node->data, ptr->size);
+
+    free(node);
+
+    return 0;
+}
+
+void llist_travel(LLIST *p, llist_op *op)
+{
+    struct llist_head_st *ptr = p;
+    struct llist_node_st *cur;
+
+    for (cur = ptr->head.next; cur != &ptr->head; cur = cur->next)
+        op(cur->data);
+}
+
+void llist_destroy(LLIST *p)
+{
+    struct llist_head_st *ptr = p;
+    struct llist_node_st *cur, *next;
+
+    for (cur = ptr->head.next; cur != &ptr->head; cur = next)
+    {
+        next = cur->next;
+        free(cur);
+    }
+
+    free(ptr);
+}
diff --git a/Chapter11/ds/line/list/linklist/double/lib4/llist.h b/Chapter11/ds/line/list/linklist/double/lib4/llist.h
new file mode 100644
index 0000000..f000d31
--- /dev/null
+++ b/Chapter11/ds/line/list/linklist/double/lib4/llist.h
@@ -0,0 +1,27 @@
+#ifndef LLIST_H__
+#define LLIST_H__
+
+#define LLIST_FORWARD  1
+#define LLIST_BACKWARD 2
+
+// !!! 实现了隐藏 LLIST 的实现方法
+typedef void LLIST;
+
+typedef void llist_op(const void *);
+typedef int  llist_cmp(const void *, const void *);
+
+LLIST *llist_create(int initsize);
+
+int llist_insert(LLIST *, const void *data, int mode);
+
+void *llist_find(LLIST *, const void *key, llist_cmp *);
+
+int llist_delete(LLIST *, const void *key, llist_cmp *);
+
+int llist_fetch(LLIST *, const void *key, llist_cmp *, void *data);
+
+void llist_travel(LLIST *, llist_op *);
+
+void llist_destroy(LLIST *);
+
+#endif
diff --git a/Chapter11/ds/line/list/linklist/double/lib4/main.c b/Chapter11/ds/line/list/linklist/double/lib4/main.c
new file mode 100644
index 0000000..e736037
--- /dev/null
+++ b/Chapter11/ds/line/list/linklist/double/lib4/main.c
@@ -0,0 +1,95 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "llist.h"
+
+#define NAMESIZE 32
+
+struct score_st
+{
+    int  id;
+    char name[NAMESIZE];
+    int  math;
+    int  chinese;
+};
+
+void print_s(const void *record)
+{
+    const struct score_st *r = record;
+
+    printf("%d %s %d %d\n", r->id, r->name, r->math, r->chinese);
+}
+
+int id_cmp(const void *key, const void *record)
+{
+    const int             *k = key;
+    const struct score_st *r = record;
+
+    return (*k - r->id);
+}
+
+int name_cmp(const void *key, const void *record)
+{
+    const char            *k = key;
+    const struct score_st *r = record;
+
+    return strcmp(k, r->name);
+}
+
+
+int main()
+{
+    LLIST          *handler;
+    int             i, ret;
+    struct score_st tmp;
+
+    handler = llist_create(sizeof(struct score_st));
+    if (NULL == handler)
+        exit(1);
+
+    for (i = 0; i < 7; i++)
+    {
+        tmp.id = i;
+        snprintf(tmp.name, NAMESIZE, "std%d", i);
+        tmp.math    = rand() % 100;
+        tmp.chinese = rand() % 100;
+
+        ret = llist_insert(handler, &tmp, LLIST_FORWARD);
+        if (ret)
+            exit(1);
+    }
+
+    llist_travel(handler, print_s);
+
+    printf("\n\n");
+
+    // int id = 3;
+    char *del_name = "std6";
+
+    // ret = llist_delete(handler, &id, id_cmp);
+    ret = llist_delete(handler, del_name, name_cmp);
+    if (ret)
+        printf("llist_deleter failed!\n");
+
+    llist_travel(handler, print_s);
+
+
+
+#if 0
+    int              id = 3;
+    struct score_st *data;
+
+    data = llist_find(handler, &id, id_cmp);
+    if (NULL == data)
+        printf("Can not find!\n");
+    else
+        print_s(data);
+
+#endif
+
+
+    llist_destroy(handler);
+
+    exit(0);
+}
\ No newline at end of file
diff --git a/Chapter11/数据结构.md b/Chapter11/数据结构.md
index c8a1454..32819fc 100644
--- a/Chapter11/数据结构.md
+++ b/Chapter11/数据结构.md
@@ -14,12 +14,20 @@
 
       会更加简单，无头的话，更改首部节点会麻烦。
 
+      头节点不仅可以作为起点，还可以作为存储信息的仓库，因为头节点只有*next是必须的。
+      
       - 单链表
         - 循环
         - 不循环
+        
       - 双向链表
+        
+        `lib`四个版本，第一个最基础完善，第二个改成了变长结构体，第三个在第二个的基础上封装了函数指针，第四个在第二个的基础上隐藏了数据结构，只暴露接口。
+        
         - 循环
         - 不循环
+        
+        学到这里可以去读一下内核有关**list**的实现，主要都是宏和内联函数。
 
   - 栈