Question

在我的程序中，用户以extjs形式选择日期和时间，然后将数据发送到服务器端（c ++程序）。在服务器程序中，日期和时间将应用于系统，如下所示：

int main(){
    string date = "2013-08-28T00:00:00";
    string newtime = "09:12";
    time_t mytime = time(0);
      struct tm* tm_ptr = localtime(&mytime);

      if (tm_ptr)
      {
        tm_ptr->tm_mon  = atoi(date.substr(5,2).c_str()) - 1;
        tm_ptr->tm_mday = atoi(date.substr(8,2).c_str());
        tm_ptr->tm_year = atoi(date.substr(0,4).c_str());
        tm_ptr->tm_min  = atoi(newtime.substr(3,2).c_str());
        tm_ptr->tm_hour  = atoi(newtime.substr(0,2).c_str());
        printf("%d\n%d\n%d\n%d\n%d\n", tm_ptr->tm_mon,tm_ptr->tm_mday,tm_ptr->tm_year,tm_ptr->tm_min,tm_ptr->tm_hour);
        const struct timeval tv = {mktime(tm_ptr), 0};
        settimeofday(&tv, 0);
    }
    return 0;
}

但是当运行此代码系统崩溃时！我还有另一个应用日期和时间的代码：

int main(){
    string date = "2013-08-28T00:00:00";
    string newtime = "09:12";
    string newdate = "";
    string monthnum = date.substr(5,2);
    string month = "";
    if(strcmp(monthnum.c_str(),"01") == 0)         month = "Jan";
    else if(strcmp(monthnum.c_str(),"02") == 0)     month = "Feb";
    else if(strcmp(monthnum.c_str(),"03") == 0)     month = "Mar";
    else if(strcmp(monthnum.c_str(),"04") == 0)     month = "Apr";
    else if(strcmp(monthnum.c_str(),"05") == 0)     month = "May";
    else if(strcmp(monthnum.c_str(),"06") == 0)     month = "Jun";
    else if(strcmp(monthnum.c_str(),"07") == 0)     month = "Jul";
    else if(strcmp(monthnum.c_str(),"08") == 0)     month = "Aug";
    else if(strcmp(monthnum.c_str(),"09") == 0)     month = "Sep";
    else if(strcmp(monthnum.c_str(),"10") == 0)     month = "Oct";
    else if(strcmp(monthnum.c_str(),"11") == 0)     month = "Nov";
    else if(strcmp(monthnum.c_str(),"12") == 0)     month = "Dec";
    newdate = "\"" + month + " " + date.substr(8,2) + " " + date.substr(0,4) + " " + newtime + "\"";
    system("date --set newdate");
    return 0;
}

运行此代码时发生错误，如下所示：日期：无效日期“newdate”

我无法理解这些代码的问题！

Answer 1

“无效日期”部分是因为它实际执行“date --set newdate”。您希望它执行“date --set [newdate variable的值]”。

更改

system("date --set newdate");

到

string cmd = "date --set ";
cmd += newdate;
system(cmd.c_str());

Answer 2

sprintf可以是另一种选择......

sprintf(newdate,"date --set %s %s %s %s", month, date.substr(8,2), date.substr(0,4), newtime);
system(newdate);

只检查变量是string类型还是上层平台支持sprintf。

在linux中的c ++程序中设置系统日期和时间

2 个答案: