消息队列读操作

#include <stdio.h>#include <sys/msg.h>#include <sys/types.h>#include <sys/ipc.h>#include <stdlib.h>#define BUFSZ 4096struct msg{    long msg_types;    char msg_buf[512];};int main(int argc,char ** argv){    int qid;    int len;    struct msg pmsg;    if(argc != 2)    {        perror("argc");    }    qid = atoi(argv[1]);    len = msgrcv(qid,&pmsg,BUFSZ,0,0);    if(len > 0)    {        pmsg.msg_buf[len] = '\0';        printf("qid %d\n",qid);        printf("msg type %d\n",pmsg.msg_types);        printf("msg text %s\n",pmsg.msg_buf);    }    else if( len  == 0)    {        printf("no message!\n");    }    else    {        perror("msgrcv\n");    }    //system("ipcs -q");    return 0;}