進程間通訊之消息隊列

#include
#include<sys/msg.h>


#define MAX_MSG_BUF_LEN    512
int iKey = 6004;


struct ipcmsgbuf
{
    long mtype;
    char mtext[MAX_MSG_BUF_LEN];
};


int main( void )
{
    int qid;
    char sTmp[128], sTmp2[128], sTmp3[128];
    struct ipcmsgbuf msgdata;


    memset( sTmp, 0, sizeof(sTmp) );

    memset( sTmp2, 0, sizeof(sTmp2) );

    memset( sTmp3, 0, sizeof(sTmp3) );

    if( (qid = msgget(iKey, 0000)) < 0 )
    {
        printf("0000\n");

        qid = msgget( iKey, IPC_CREAT|0660 );

        if( qid < 0 )
        {
            printf( "msgget error!\n" );
            return -1;
        }
    }

    /* 寫消息隊列 */
    memset( &msgdata, 0, sizeof( struct ipcmsgbuf ) );
    msgdata.mtype = 1;
    memcpy( msgdata.mtext, "abcdefg", 7 );
    msgsnd( qid, &msgdata, 7, 0 );

    /* 寫消息隊列 */
    memset( &msgdata, 0, sizeof( struct ipcmsgbuf ) );
    msgdata.mtype = 2;
    memcpy( msgdata.mtext, "1234567", 7 );
    msgsnd( qid, &msgdata, 7, 0 );

    /* 讀消息隊列 */
    memset( &msgdata, 0, sizeof( struct ipcmsgbuf ) );
    msgrcv( qid, &msgdata, 7, 1, 0 );
    memcpy( sTmp, msgdata.mtext, 7 );
    printf( "sTmp=%s\n", sTmp );

    /* 讀消息隊列 */

    memset( &msgdata, 0, sizeof( struct ipcmsgbuf ) );
    msgrcv( qid, &msgdata, 7, 2, 0 );
    memcpy( sTmp2, msgdata.mtext, 7 );
    printf( "sTmp2=%s\n", sTmp2 );

    /* 讀消息隊列 */
    memset( &msgdata, 0, sizeof( struct ipcmsgbuf ) );
    msgrcv( qid, &msgdata, 7, 2, IPC_NOWAIT );
    memcpy( sTmp3, msgdata.mtext, 7 );
    printf( "sTmp3=%s\n", sTmp3 );

    /* 從系統中刪除該消息隊列以及仍在該隊列上的所有數據 */
    msgctl( qid, IPC_RMID, 0 );


    return 0;
}

運行結果：

0000

sTmp=abcdefg
sTmp2=1234567
sTmp3=