GHashTable,使用uint64_t作为键,并使用struct作为值 [英] GHashTable that using uint64_t as key and a struct as value
问题描述
我正在学习GHashTable
.尽管Stackoverflow中已经有一些示例,但它们只是一些常见情况.因此,我仍然不确定如何执行我的要求并决定寻求帮助.
我想使用uint64_t
作为键,并使用struct
作为值.我发现GLib
中没有这样的内置哈希函数.只有一个g_int64_hash()
.尽管密钥是uint64_t
,但大约只有52位.所以我认为gint64
可以.但是我看到一些使用GINT_TO_POINTER()
转换值的示例(有时没有).因此,请对此感到困惑.
非常感谢!
I am studying the GHashTable
. Though there are already some examples in Stackoverflow, they are just some common case. So I am still not sure how to implement my requirements and decide to ask for help.
I want to use a uint64_t
as key and a struct
as value. I find that there is no such built-in hash function in GLib
. There is just a g_int64_hash()
. Though the key is uint64_t
, it will just be about 52 bits. So I think gint64
is OK. But I see some examples using GINT_TO_POINTER()
to convert the value (and sometimes they didn't). So just be confused about this.
Thanks very much!
推荐答案
请参见 ghash.c
g_int64_hash
和g_int64_equal
的实现方式:
See in ghash.c
how g_int64_hash
and g_int64_equal
are implemented:
...
gboolean
g_int64_equal (gconstpointer v1,
gconstpointer v2)
{
return *((const gint64*) v1) == *((const gint64*) v2);
}
...
guint
g_int64_hash (gconstpointer v)
{
return (guint) *(const gint64*) v;
}
...
您可以类似地写出赢取的uint64_t_hash
和uint64_equal
:
You can write your won uint64_t_hash
and uint64_equal
similarly:
gboolean
uint64_t_equal (gconstpointer v1,
gconstpointer v2)
{
return *((const uint64_t*) v1) == *((const uint64_t*) v2);
}
guint
uint64_t_hash (gconstpointer v)
{
return (guint) *(const uint64_t*) v;
}
查看示例:
#include <glib.h>
#include <stdio.h>
#include <inttypes.h>
/* the value structure */
typedef struct __MyStruct
{
int a;
int b;
} MyStruct;
/* the hash equality function */
static gboolean
uint64_t_equal (gconstpointer v1,
gconstpointer v2)
{
return *((const uint64_t*) v1) == *((const uint64_t*) v2);
}
/* the hash function */
static guint
uint64_t_hash (gconstpointer v)
{
return (guint) *(const uint64_t*) v;
}
/* the hash function */
static void
print_hash(gpointer key,
gpointer value,
gpointer user_data)
{
printf("%" PRIu64 " = {%d, %d}\n",
*(uint64_t*) key, ((MyStruct *) value)->a, ((MyStruct *) value)->b);
}
int
main(int argc, char **argv)
{
GHashTable *hash;
/* key => value */
uint64_t k1 = 11; MyStruct s1 = {1, 11};
uint64_t k2 = 22; MyStruct s2 = {2, 22};
uint64_t k3 = 33; MyStruct s3 = {3, 33};
hash = g_hash_table_new(uint64_t_hash, uint64_t_equal);
/* insert values */
g_hash_table_insert(hash, &k1, &s1);
g_hash_table_insert(hash, &k2, &s2);
g_hash_table_insert(hash, &k3, &s3);
/* iterate over the values in the hash table */
g_hash_table_foreach(hash, print_hash, NULL);
g_hash_table_destroy(hash);
return 0;
}
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