glib库队列GQueue介绍

最新推荐文章于 2024-11-16 22:42:03 发布

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最新推荐文章于 2024-11-16 22:42:03 发布

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本文通过示例介绍了glib库中的GQueue双端队列数据结构，演示了如何在其两端添加和删除数据，并展示了队列的其他操作。

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come from:http://blog.youkuaiyun.com/plusboy/article/details/1492570
队列是一种向最后添加条目，从最前删除条目的数据结构，这种数据结构在处理按顺序到达的数据是很有用。glib库提供的队列GQueue是一个双端队列，它的实现基础是双向链表，所以它支持在队列的两端进行添加和删除，也支持很多其它的操作，比如在队列中进行插入和删除，但是我不推荐使用这样的功能，因为当你经常需要在队列中进行插入和删除的时候，链表或许是个更好的选择。

下面的代码演示利用glib库中的GQueue向队头、队尾添加数据和从队头、队尾删除数据的操作。

/***************************************************************************
  file: g_queue.c
  desc: 这个文件用于演示glib库中队列的基本操作
  compile: gcc -o g_queue g_queue.c `pkg-config --cflags --libs glib-2.0`
***************************************************************************/

#include < glib.h >

void display_queue(GQueue * queue, const char * prompt)
{
     int len = g_queue_get_length(queue);
     int i = 0 ;

    printf( " %s: /n " , prompt);
     for (i = 0 ; i < len; i ++ ) {
        printf( " %s " , g_queue_peek_nth(queue, i));
    }
    printf( " /n " );
}

int main( int argc, char * argv[])
{
    GQueue * queue = NULL;

    queue = g_queue_new();
    printf( " The queue is empty? %s " , g_queue_is_empty(queue) ? " YES " : " NO " );

    g_queue_push_head(queue, " first " );
    g_queue_push_head(queue, " second " );
    g_queue_push_head(queue, " third " );
    display_queue(queue, " After push first, second and third at head of queue " );

    g_queue_push_tail(queue, " one " );
    g_queue_push_tail(queue, " two " );
    g_queue_push_tail(queue, " three " );
    printf( " After push one, two and three at tail of queue:/n " );
    g_queue_foreach(queue, (GFunc)printf, NULL);
    printf( " /n " );

    printf( " pop tail of queue: %s " , g_queue_pop_tail(queue));
    display_queue(queue, " After pop tail " );

    printf( " pop head of queue: %s /n " , g_queue_pop_head(queue));
    display_queue(queue, " After pop head " );

     /* queue index start from 0 */
    printf( " pop 2nd of queue: %s /n " , g_queue_pop_nth(queue, 1 ));
    display_queue(queue, " After pop second " );

    g_queue_remove(queue, " second " );
    display_queue(queue, " After remove second " );

    GList * list = NULL;

    list = g_queue_peek_nth_link(queue, 1 );
    g_queue_insert_before(queue, list, " 10 " );
    g_queue_insert_after(queue, list, " 20 " );
    display_queue(queue, " After insert 10 before index 1 and 20 after index 1 " );

    g_queue_free(queue);

     return 0 ;
}

编译程序

[plusboy@localhost c]$ gcc -o g_queue g_queue.c `pkg-config --cflags --libs glib-2.0`

程序执行结果

/**********************************************************

[plus@localhost c]$ ./g_queue
The queue is empty? YES
After push first, second and third at head of queue:
third second first
After push one, two and three at tail of queue:
third second first one two three
pop tail of queue: three
After pop tail:
third second first one two
pop head of queue: third
After pop head:
second first one two
pop 2nd of queue: first
After pop second:
second one two
After remove second:
one two
After insert 10 before index 1 and 20 after index 1:
one 10 two 20

***********************************************************/

说明：
1、向队列里添加和从队列里删除条目不返回任何值，所以为了再次使用队列要保存g_queue_new()返回的队列指针。
2、在队列的两端、中间都可以插入和删除条目，这就像排队的时候有人要插队，有人没排到就走了。
3、g_queue_peek_*函数可以取出队列中条目的内容进行检查，而不用从队列中删除该条目