c语言字典库的使用,实现键值对查找,以字符串为Key,以指针为Value
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2022-07-14 18:46:29
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c语言字典库的使用,实现键值对查找,以字符串为Key,以指针为Value
dictionary库的使用
前不久，一直在找一个c语言版的hash键值对库，找到一个dictionary库，是以字符串为key，以字符串为value的键值对库，但是我需要的是以字符串为key，以任意指针为value的键值对库，这样我就可以用函数名，去查找函数指针，并调用函数；也可以用对象名，去找结构体指针。所以我这里对原版的dictionary库做了一点小修改，以满足我的需求
dictionary库源码
dictionary.c文件内容
/*-------------------------------------------------------------------------*/
/**
@file dictionary.c
@author N. Devillard
@brief Implements a dictionary for string variables.
This module implements a simple dictionary object, i.e. a list
of string/string associations. This object is useful to store e.g.
informations retrieved from a configuration file (ini files).
*/
/*--------------------------------------------------------------------------*/
/*---------------------------------------------------------------------------
Includes
---------------------------------------------------------------------------*/
#include "dictionary.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
/** Maximum value size for integers and doubles. */
#define MAXVALSZ 1024
/** Minimal allocated number of entries in a dictionary */
#define DICTMINSZ 128
/** Invalid key token */
#define DICT_INVALID_KEY ((char*)-1)
/*---------------------------------------------------------------------------
Private functions
---------------------------------------------------------------------------*/
/* Doubles the allocated size associated to a pointer */
/* 'size' is the current allocated size. */
static void * mem_double(void * ptr, int size)
{
void * newptr ;
newptr = calloc(2*size, 1);
if (newptr==NULL) {
return NULL ;
}
memcpy(newptr, ptr, size);
free(ptr);
return newptr ;
}
/*-------------------------------------------------------------------------*/
/**
@brief Duplicate a string
@param s String to duplicate
@return Pointer to a newly allocated string, to be freed with free()
This is a replacement for strdup(). This implementation is provided
for systems that do not have it.
*/
/*--------------------------------------------------------------------------*/
static char * xstrdup(const char * s)
{
char * t ;
if (!s)
return NULL ;
t = (char*)malloc(strlen(s)+1) ;
if (t) {
strcpy(t,s);
}
return t ;
}
/*---------------------------------------------------------------------------
Function codes
---------------------------------------------------------------------------*/
/*-------------------------------------------------------------------------*/
/**
@brief Compute the hash key for a string.
@param key Character string to use for key.
@return 1 unsigned int on at least 32 bits.
This hash function has been taken from an Article in Dr Dobbs Journal.
This is normally a collision-free function, distributing keys evenly.
The key is stored anyway in the struct so that collision can be avoided
by comparing the key itself in last resort.
*/
/*--------------------------------------------------------------------------*/
unsigned dictionary_hash(const char * key)
{
int len ;
unsigned hash ;
int i ;
len = strlen(key);
for (hash=0, i=0 ; i<len ; i++) {
hash += (unsigned)key[i] ;
hash += (hash<<10);
hash ^= (hash>>6) ;
}
hash += (hash <<3);
hash ^= (hash >>11);
hash += (hash <<15);
return hash ;
}
/*-------------------------------------------------------------------------*/
/**
@brief Create a new dictionary object.
@param size Optional initial size of the dictionary.
@return 1 newly allocated dictionary objet.
This function allocates a new dictionary object of given size and returns
it. If you do not know in advance (roughly) the number of entries in the
dictionary, give size=0.
*/
/*--------------------------------------------------------------------------*/
dictionary * dictionary_new(int size)
{
dictionary * d ;
/* If no size was specified, allocate space for DICTMINSZ */
if (size<DICTMINSZ) size=DICTMINSZ ;
if (!(d = (dictionary *)calloc(1, sizeof(dictionary)))) {
return NULL;
}
d->size = size ;
d->val = (void **)calloc(size, sizeof(void*));
d->key = (char **)calloc(size, sizeof(char*));
d->hash = (unsigned int *)calloc(size, sizeof(unsigned));
return d ;
}
/*-------------------------------------------------------------------------*/
/**
@brief Delete a dictionary object
@param d dictionary object to deallocate.
@return void
Deallocate a dictionary object and all memory associated to it.
*/
/*--------------------------------------------------------------------------*/
void dictionary_del(dictionary * d)
{
int i ;
if (d==NULL) return ;
for (i=0 ; i<d->size ; i++) {
if (d->key[i]!=NULL)
free(d->key[i]);
// if (d->val[i]!=NULL) //当存的指针为malloc的堆空间时
// free(d->val[i]);
}
free(d->val);
free(d->key);
free(d->hash);
free(d);
return ;
}
/*-------------------------------------------------------------------------*/
/**
@brief Get a value from a dictionary.
@param d dictionary object to search.
@param key Key to look for in the dictionary.
@param def Default value to return if key not found.
@return 1 pointer to internally allocated character string.
This function locates a key in a dictionary and returns a pointer to its
value, or the passed 'def' pointer if no such key can be found in
dictionary. The returned character pointer points to data internal to the
dictionary object, you should not try to free it or modify it.
*/
/*--------------------------------------------------------------------------*/
void * dictionary_get(dictionary * d, const char * key, void * def)
{
unsigned hash ;
int i ;
hash = dictionary_hash(key);
for (i=0 ; i<d->size ; i++) {
if (d->key[i]==NULL)
continue ;
/* Compare hash */
if (hash==d->hash[i]) {
/* Compare string, to avoid hash collisions */
if (!strcmp(key, d->key[i])) {
return d->val[i] ;
}
}
}
return def ;
}
/*-------------------------------------------------------------------------*/
/**
@brief Set a value in a dictionary.
@param d dictionary object to modify.
@param key Key to modify or add.
@param val Value to add.
@return int 0 if Ok, anything else otherwise
If the given key is found in the dictionary, the associated value is
replaced by the provided one. If the key cannot be found in the
dictionary, it is added to it.
It is Ok to provide a NULL value for val, but NULL values for the dictionary
or the key are considered as errors: the function will return immediately
in such a case.
Notice that if you dictionary_set a variable to NULL, a call to
dictionary_get will return a NULL value: the variable will be found, and
its value (NULL) is returned. In other words, setting the variable
content to NULL is equivalent to deleting the variable from the
dictionary. It is not possible (in this implementation) to have a key in
the dictionary without value.
This function returns non-zero in case of failure.
*/
/*--------------------------------------------------------------------------*/
int dictionary_set(dictionary * d, const char * key, void * val)
{
int i ;
unsigned hash ;
if (d==NULL || key==NULL) return -1 ;
/* Compute hash for this key */
hash = dictionary_hash(key) ;
/* Find if value is already in dictionary */
if (d->n>0) {
for (i=0 ; i<d->size ; i++) {
if (d->key[i]==NULL)
continue ;
if (hash==d->hash[i]) { /* Same hash value */
if (!strcmp(key, d->key[i])) { /* Same key */
/* Found a value: modify and return */
d->val[i] = val;
/* Value has been modified: return */
return 0 ;
}
}
}
}
/* Add a new value */
/* See if dictionary needs to grow */
if (d->n==d->size) {
/* Reached maximum size: reallocate dictionary */
d->val = (void **)mem_double(d->val, d->size * sizeof(void*)) ;
d->key = (char **)mem_double(d->key, d->size * sizeof(char*)) ;
d->hash = (unsigned int *)mem_double(d->hash, d->size * sizeof(unsigned)) ;
if ((d->val==NULL) || (d->key==NULL) || (d->hash==NULL)) {
/* Cannot grow dictionary */
return -1 ;
}
/* Double size */
d->size *= 2 ;
}
/* Insert key in the first empty slot. Start at d->n and wrap at
d->size. Because d->n < d->size this will necessarily
terminate. */
for (i=d->n ; d->key[i] ; ) {
if(++i == d->size) i = 0;
}
/* Copy key */
d->key[i] = xstrdup(key);
d->val[i] = val;
d->hash[i] = hash;
d->n ++ ;
return 0 ;
}
/*-------------------------------------------------------------------------*/
/**
@brief Delete a key in a dictionary
@param d dictionary object to modify.
@param key Key to remove.
@return void
This function deletes a key in a dictionary. Nothing is done if the
key cannot be found.
*/
/*--------------------------------------------------------------------------*/
void dictionary_unset(dictionary * d, const char * key)
{
unsigned hash ;
int i ;
if (key == NULL) {
return;
}
hash = dictionary_hash(key);
for (i=0 ; i<d->size ; i++) {
if (d->key[i]==NULL)
continue ;
/* Compare hash */
if (hash==d->hash[i]) {
/* Compare string, to avoid hash collisions */
if (!strcmp(key, d->key[i])) {
/* Found key */
break ;
}
}
}
if (i>=d->size)
/* Key not found */
return ;
free(d->key[i]);
d->key[i] = NULL ;
if (d->val[i]!=NULL) {
d->val[i] = NULL ;
}
d->hash[i] = 0 ;
d->n -- ;
return ;
}
dictionary.h文件内容
/*-------------------------------------------------------------------------*/
/**
@file dictionary.h
@author N. Devillard
@brief Implements a dictionary for string variables.
This module implements a simple dictionary object, i.e. a list
of string/string associations. This object is useful to store e.g.
informations retrieved from a configuration file (ini files).
*/
/*--------------------------------------------------------------------------*/
#ifndef _DICTIONARY_H_
#define _DICTIONARY_H_
/*---------------------------------------------------------------------------
Includes
---------------------------------------------------------------------------*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
/*---------------------------------------------------------------------------
New types
---------------------------------------------------------------------------*/
/*-------------------------------------------------------------------------*/
/**
@brief Dictionary object
This object contains a list of string/string associations. Each
association is identified by a unique string key. Looking up values
in the dictionary is speeded up by the use of a (hopefully collision-free)
hash function.
*/
/*-------------------------------------------------------------------------*/
typedef struct _dictionary_ {
int n ; /** Number of entries in dictionary */
int size ; /** Storage size */
void ** val ; /** List of string values */
char ** key ; /** List of string keys */
unsigned * hash ; /** List of hash values for keys */
} dictionary ;
/*---------------------------------------------------------------------------
Function prototypes
---------------------------------------------------------------------------*/
/*-------------------------------------------------------------------------*/
/**
@brief Compute the hash key for a string.
@param key Character string to use for key.
@return 1 unsigned int on at least 32 bits.
This hash function has been taken from an Article in Dr Dobbs Journal.
This is normally a collision-free function, distributing keys evenly.
The key is stored anyway in the struct so that collision can be avoided
by comparing the key itself in last resort.
*/
/*--------------------------------------------------------------------------*/
unsigned dictionary_hash(const char * key);
/*-------------------------------------------------------------------------*/
/**
@brief Create a new dictionary object.
@param size Optional initial size of the dictionary.
@return 1 newly allocated dictionary objet.
This function allocates a new dictionary object of given size and returns
it. If you do not know in advance (roughly) the number of entries in the
dictionary, give size=0.
*/
/*--------------------------------------------------------------------------*/
dictionary * dictionary_new(int size);
/*-------------------------------------------------------------------------*/
/**
@brief Delete a dictionary object
@param d dictionary object to deallocate.
@return void
Deallocate a dictionary object and all memory associated to it.
*/
/*--------------------------------------------------------------------------*/
void dictionary_del(dictionary * vd);
/*-------------------------------------------------------------------------*/
/**
@brief Get a value from a dictionary.
@param d dictionary object to search.
@param key Key to look for in the dictionary.
@param def Default value to return if key not found.
@return 1 pointer to internally allocated character string.
This function locates a key in a dictionary and returns a pointer to its
value, or the passed 'def' pointer if no such key can be found in
dictionary. The returned character pointer points to data internal to the
dictionary object, you should not try to free it or modify it.
*/
/*--------------------------------------------------------------------------*/
void * dictionary_get(dictionary * d, const char * key, void * def);
/*-------------------------------------------------------------------------*/
/**
@brief Set a value in a dictionary.
@param d dictionary object to modify.
@param key Key to modify or add.
@param val Value to add.
@return int 0 if Ok, anything else otherwise
If the given key is found in the dictionary, the associated value is
replaced by the provided one. If the key cannot be found in the
dictionary, it is added to it.
It is Ok to provide a NULL value for val, but NULL values for the dictionary
or the key are considered as errors: the function will return immediately
in such a case.
Notice that if you dictionary_set a variable to NULL, a call to
dictionary_get will return a NULL value: the variable will be found, and
its value (NULL) is returned. In other words, setting the variable
content to NULL is equivalent to deleting the variable from the
dictionary. It is not possible (in this implementation) to have a key in
the dictionary without value.
This function returns non-zero in case of failure.
*/
/*--------------------------------------------------------------------------*/
int dictionary_set(dictionary * vd, const char * key, void * val);
/*-------------------------------------------------------------------------*/
/**
@brief Delete a key in a dictionary
@param d dictionary object to modify.
@param key Key to remove.
@return void
This function deletes a key in a dictionary. Nothing is done if the
key cannot be found.
*/
/*--------------------------------------------------------------------------*/
void dictionary_unset(dictionary * d, const char * key);
#endif
dictionary的接口说明
- 传入字典成员个数，创建一个字典，并返回
dictionary * dictionary_new(int size); - 给字典中添加元素，以字符串为key，以指针为value
int dictionary_set(dictionary * vd, const char * key, void * val); - 删除字典中的元素
void dictionary_unset(dictionary * d, const char * key); - 获取字典中的元素， 第三个参数为默认值，不存在就返回默认值
void * dictionary_get(dictionary * d, const char * key, void * def); - 销毁一个字典，释放空间，若保存的value值指针，是自己申请的堆空间，需要自己free
void dictionary_del(dictionary * vd);
dictionary使用测试
#include <stdio.h>
#include <sys/time.h>
#include "dictionary.h"
#define TEMP_SIZE 128
typedef void (*skill_f)(char *);
struct student
{
int id; // 编号
int age; // 年龄
char name[TEMP_SIZE]; // 姓名
char addr[TEMP_SIZE]; // 地址
char skill[TEMP_SIZE]; // 技能名,即函数名
};
void play_table_tennis(char * name)
{
printf("我是%s, 我会打乒乓球\n", name);
}
void eat_food(char * name)
{
printf("我是%s, 我很会吃\n", name);
}
void no_skill(char * name)
{
printf("我是%s, 我无能, 我是废物\n", name);
}
/**定义数据变量, 可以从配置文件中读取, 这里只做简单定义*/
struct student students[3] = {
{0, 10, "小明", "湖南省长沙市", "play_table_tennis"},
{1, 10, "小红", "湖南省株洲市", "eat_food"},
{2, 10, "小华", "江西省南昌市", "no_skill"},
};
void display(dictionary * std_dic, dictionary * skill_dic, char * name)
{
struct student * p = dictionary_get(std_dic, name, NULL); //从字典中读取
if (!p)
return;
printf("id：%d\t 姓名：%s\t 年龄：%d\t 地址：%s\t", p->id, p->name, p->age, p->addr);
/*根据函数名, 读取函数指针*/
skill_f func = (skill_f)(dictionary_get(skill_dic, p->skill, no_skill));
func(p->name);
}
int main(int argc, char * argv[])
{
//初始化30个存储空间，若不够，会自动翻倍，变为60个
dictionary * std_dic = dictionary_new(30);
dictionary * skill_dic = dictionary_new(10);
/*技能字典, 将函数地址放入字典中, 以后可以通过函数名, 获取函数指针, 并执行函数*/
dictionary_set(skill_dic, "play_table_tennis", play_table_tennis);
dictionary_set(skill_dic, "eat_food", eat_food);
dictionary_set(skill_dic, "no_skill", no_skill);
/*学生字典, 将结构体指针放入*/
dictionary_set(std_dic, "小明", &students[0]);
dictionary_set(std_dic, "小红", &students[1]);
dictionary_set(std_dic, "小华", &students[2]);
/*测试*/
display(std_dic, skill_dic, "小红");// 查找打印
/*销毁*/
dictionary_del(std_dic);
dictionary_del(skill_dic);
return 0;
}
测试结果如下
[email protected]:~/桌面/code/c/test/testDictionary$ gcc -o main main.c dictionary.c
[email protected]:~/桌面/code/c/test/testDictionary$ ./main
id：1 姓名：小红 年龄：10 地址：湖南省株洲市 我是小红, 我很会吃