查找树，俄罗斯方块，系统编程开始

Chapter11/ds/tree/retrieval/Makefile

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+# 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: $(TARGET)
+
+LDFLAGS=-L/usr/local/lib
+
+# LDLIBS=-lqueue -lllist
+
+# 第一行依赖关系：冒号后面为依赖的文件，相当于Hello: main.o a.o b.o
+# 第二行规则：$@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) $(LDFLAGS) -o $@ $^ $(LDLIBS)
+
+# 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)

Chapter11/ds/tree/retrieval/trie.c

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+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#define DESC_SIZE 256
+#define KEY_SIZE  256
+#define BUFSIZE   512
+#define FNAME     "log"
+
+struct node_st
+{
+    struct node_st *ch[26];
+    char            desc[DESC_SIZE];
+};
+
+static int get_word(FILE *fp, char *key, char *desc)
+{
+    char  buf[BUFSIZE];
+    char *retp;
+    int   i, j;
+
+    retp = fgets(buf, BUFSIZE, fp);
+    if (NULL == retp)
+        return -1;
+
+    for (i = 0; i < KEY_SIZE - 1 && buf[i] != ':'; i++)
+        key[i] = buf[i];
+    key[i] = '\0';
+
+    i++;
+
+    for (j = 0; j < DESC_SIZE - 1 && buf[i] != '\0'; j++, i++)
+        desc[j] = buf[i];
+    desc[j] = '\0';
+
+    return 0;
+}
+
+static struct node_st *newnode()
+{
+    struct node_st *node;
+    int             i;
+
+    node = malloc(sizeof(*node));
+    if (NULL == node)
+        return NULL;
+
+    node->desc[0] = '\0';
+
+    for (i = 0; i < 26; i++)
+        node->ch[i] = NULL;
+
+    return node;
+}
+
+static int insert(struct node_st **root, char *key, char *desc)
+{
+    if (NULL == *root)
+    {
+        *root = newnode();
+        if (NULL == *root)
+            return -1;
+    }
+
+    if ('\0' == *key)
+    {
+        strcpy((*root)->desc, desc);
+        return 0;
+    }
+
+    return insert((*root)->ch + *key - 'a', key + 1, desc);
+}
+
+static char *find(struct node_st *root, char *key)
+{
+    if (NULL == root)
+        return NULL;
+
+    if ('\0' == *key)
+        return root->desc;
+
+    return find(root->ch[*key - 'a'], key + 1);
+}
+
+int main()
+{
+    struct node_st *tree;
+    FILE           *fp;
+    char            desc[DESC_SIZE] = {'\0'}, key[KEY_SIZE] = {'\0'};
+    int             ret;
+    char           *datap;
+
+    fp = fopen(FNAME, "r");
+    if (NULL == fp)
+    {
+        fprintf(stderr, "fopen():error!\n");
+        exit(1);
+    }
+
+    while (1)
+    {
+        ret = get_word(fp, key, desc);
+        if (-1 == ret)
+            break;
+
+        // puts(key);
+        // puts(desc);
+
+        insert(&tree, key, desc);
+    }
+
+    datap = find(tree, "donkey");
+    if (NULL == datap)
+        printf("Can not find!\n");
+    else
+        puts(datap);
+
+    fclose(fp);
+
+    exit(0);
+}