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编译：gcc -g -Wall -O0 fuck.c -o fuck `pkg-config --libs --cflags glib-2.0`
1
一些简单的散列表操作 有错误需要调试
这里是一些示例，可以生动地展示以上的理论： #include < glib.h > #include < stdio.h > int main( int argc, char ** argv) { GHashTable * hash = g_hash_table_new(g_str_hash, g_str_equal); g_hash_table_insert(hash, " Virginia " , " Richmond " ); g_hash_table_insert(hash, " Texas " , " Austin " ); g_hash_table_insert(hash, " Ohio " , " Columbus " ); printf( " There are %d keys in the hash\n " , g_hash_table_size(hash)); printf( " The capital of Texas is %s\n " , g_hash_table_lookup(hash, " Texas " )); gboolean found = g_hash_table_remove(hash, " Virginia " ); printf( " The value 'Virginia' was %sfound and removed\n " , found ? "" : " not " ); g_hash_table_destroy(hash); return 0 ;}
***** Output *****There are 3 keys in the hashThe capital of Texas is AustinThe value 'Virginia' was found and removed
2
插入和替换值
当使用 g_hash_table_insert 插入键时，GHashTable 首先检查那个键是否已经存在。如果已经存在，那么那个值会被替换，而键不会被替换。如果希望同时替换键和值，那么需要使用 g_hash_table_replace。它稍有不同，因此在下面同时展示了二者：
#include < glib.h > #include < stdio.h > static char * texas_1, * texas_2; void key_destroyed(gpointer data) { printf( " Got a key destroy call for %s\n " , data == texas_1 ? " texas_1 " : " texas_2 " );} int main( int argc, char ** argv) { GHashTable * hash = g_hash_table_new_full(g_str_hash, g_str_equal, (GDestroyNotify)key_destroyed, NULL); texas_1 = g_strdup( " Texas " ); texas_2 = g_strdup( " Texas " ); g_hash_table_insert(hash, texas_1, " Austin " ); printf( " Calling insert with the texas_2 key\n " ); g_hash_table_insert(hash, texas_2, " Houston " ); printf( " Calling replace with the texas_2 key\n " ); g_hash_table_replace(hash, texas_2, " Houston " ); printf( " Destroying hash, so goodbye texas_2\n " ); g_hash_table_destroy(hash); g_free(texas_1); g_free(texas_2); return 0 ;}
***** Output *****Calling insert with the texas_2 keyGot a key destroy call for texas_2Calling replace with the texas_2 keyGot a key destroy call for texas_1Destroying hash, so goodbye texas_2Got a key destroy call for texas_2
3
遍历 键/值 对
有时需要遍历所有的 键/值 对。这里是如何使用 g_hash_table_foreach 来完成那项任务： #include < glib.h > #include < stdio.h > void iterator(gpointer key, gpointer value, gpointer user_data) { printf(user_data, * (gint * )key, value);} int main( int argc, char ** argv) { GHashTable * hash = g_hash_table_new(g_int_hash, g_int_equal); gint * k_one = g_new(gint, 1 ), * k_two = g_new(gint, 1 ), * k_three = g_new(gint, 1 ); * k_one = 1 , * k_two = 2 , * k_three = 3 ; g_hash_table_insert(hash, k_one, " one " ); g_hash_table_insert(hash, k_two, " four " ); g_hash_table_insert(hash, k_three, " nine " ); g_hash_table_foreach(hash, (GHFunc)iterator, " The square of %d is %s\n " ); g_hash_table_destroy(hash); return 0 ;}
***** Output *****The square of 1 is oneThe square of 2 is fourThe square of 3 is nine
查找条目
使用 g_hash_table_find 函数来查找某个特定的值。这个函数支持查看每一个 键/值 对，直到定位到期望的值。这里是一个示例： #include < glib.h > #include < stdio.h > void value_destroyed(gpointer data) { printf( " Got a value destroy call for %d\n " , GPOINTER_TO_INT(data));}gboolean finder(gpointer key, gpointer value, gpointer user_data) { return (GPOINTER_TO_INT(key) + GPOINTER_TO_INT(value)) == 42 ;} int main( int argc, char ** argv) { GHashTable * hash = g_hash_table_new_full(g_direct_hash, g_direct_equal, NULL, (GDestroyNotify)value_destroyed); g_hash_table_insert(hash, GINT_TO_POINTER( 6 ), GINT_TO_POINTER( 36 )); g_hash_table_insert(hash, GINT_TO_POINTER( 10 ), GINT_TO_POINTER( 12 )); g_hash_table_insert(hash, GINT_TO_POINTER( 20 ), GINT_TO_POINTER( 22 )); gpointer item_ptr = g_hash_table_find(hash, (GHRFunc)finder, NULL); gint item = GPOINTER_TO_INT(item_ptr); printf( " %d + %d == 42\n " , item, 42 - item); g_hash_table_destroy(hash); return 0 ;}
***** Output *****36 + 6 == 42Got a value destroy call for 36Got a value destroy call for 22Got a value destroy call for 12
5
难处理的情形：从表中删除
偶尔可能需要从一个 GHashTable 中删除某个条目，但却没有获得 GHashTable 所提供的任意 GDestroyNotify 函数的回调。要完成此任务，或者可以根据具体的键使用 g_hash_table_steal，或者根据所有匹配某个条件的键使用 g_hash_table_foreach_steal。
#include < glib.h > #include < stdio.h > gboolean wide_open(gpointer key, gpointer value, gpointer user_data) { return TRUE;} void key_destroyed(gpointer data) { printf( " Got a GDestroyNotify callback\n " );} int main( int argc, char ** argv) { GHashTable * hash = g_hash_table_new_full(g_str_hash, g_str_equal, (GDestroyNotify)key_destroyed, (GDestroyNotify)key_destroyed); g_hash_table_insert(hash, " Texas " , " Austin " ); g_hash_table_insert(hash, " Virginia " , " Richmond " ); g_hash_table_insert(hash, " Ohio " , " Columbus " ); g_hash_table_insert(hash, " Oregon " , " Salem " ); g_hash_table_insert(hash, " New York " , " Albany " ); printf( " Removing New York, you should see two callbacks\n " ); g_hash_table_remove(hash, " New York " ); if (g_hash_table_steal(hash, " Texas " )) { printf( " Texas has been stolen, %d items remaining\n " , g_hash_table_size(hash)); } printf( " Stealing remaining items\n " ); g_hash_table_foreach_steal(hash, (GHRFunc)wide_open, NULL); printf( " Destroying the GHashTable, but it's empty, so no callbacks\n " ); g_hash_table_destroy(hash); return 0 ;}
***** Output *****Removing New York, you should see two callbacksGot a GDestroyNotify callbackGot a GDestroyNotify callbackTexas has been stolen, 3 items remainingStealing remaining itemsDestroying the GHashTable, but it's empty, so no callbacks
6
高级查找：找到键和值
针对需要从表中同时获得键和值的情况，GHashTable 提供了一个 g_hash_table_lookup_extended 函数。它与 g_hash_table_lookup 非常类似，但要接受更多两个参数。这些都是“out”参数；也就是说，它们是双重间接指针，当数据被定位时将指向它
。这里是它的工作方式：
#include < glib.h > #include < stdio.h > int main( int argc, char ** argv) { GHashTable * hash = g_hash_table_new(g_str_hash, g_str_equal); g_hash_table_insert(hash, " Texas " , " Austin " ); g_hash_table_insert(hash, " Virginia " , " Richmond " ); g_hash_table_insert(hash, " Ohio " , " Columbus " ); char * state = NULL; char * capital = NULL; char ** key_ptr = & state; char ** value_ptr = & capital; gboolean result = g_hash_table_lookup_extended(hash, " Ohio " , (gpointer * )key_ptr, (gpointer * )value_ptr); if (result) { printf( " Found that the capital of %s is %s\n " , capital, state); } if ( ! g_hash_table_lookup_extended(hash, " Vermont " , (gpointer * )key_ptr, (gpointer * )value_ptr)) { printf( " Couldn't find Vermont in the hash table\n " ); } g_hash_table_destroy(hash); return 0 ;}
***** Output *****Found that the capital of Columbus is OhioCouldn't find Vermont in the hash table
7
每个键多个值 有错误需要调试
到目前为止已经介绍了每个键只拥有一个值的散列。不过有时您需要让一个键持有多个值。当出现这种需求时，使用 GSList 作为值并及 GSList 添加新的值通常是一个好的解决方案。不过，这需要稍多一些工作，如本例中所示：
#include < glib.h > #include < stdio.h > void print(gpointer key, gpointer value, gpointer data) { printf( " Here are some cities in %s: " , key); g_slist_foreach((GSList * )value, (GFunc)printf, NULL); printf( " \n " );} void destroy(gpointer key, gpointer value, gpointer data) { printf( " Freeing a GSList, first item is %s\n " , ((GSList * )value) -> data); g_slist_free(value);} int main( int argc, char ** argv) { GHashTable * hash = g_hash_table_new(g_str_hash, g_str_equal); g_hash_table_insert(hash, " Texas " , g_slist_append(g_hash_table_lookup(hash, " Texas " ), " Austin " )); g_hash_table_insert(hash, " Texas " , g_slist_append(g_hash_table_lookup(hash, " Texas " ), " Houston " )); g_hash_table_insert(hash, " Virginia " , g_slist_append(g_hash_table_lookup(hash, " Virginia " ), " Richmond " )); g_hash_table_insert(hash, " Virginia " , g_slist_append(g_hash_table_lookup(hash, " Virginia " ), " Keysville " )); g_hash_table_foreach(hash, print, NULL); g_hash_table_foreach(hash, destroy, NULL); g_hash_table_destroy(hash); return 0 ;}
***** Output *****Here are some cities in Texas: Austin HoustonHere are some cities in Virginia: Richmond KeysvilleFreeing a GSList, first item is AustinFreeing a GSList, first item is Richmond
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