原始地址:python类库中文翻译:select — 等待 I/O 完成 15.1 select — Waiting for I/O completion This module provides access to the select() and poll() functions available in most operating systems. Note that on Windows, it only works for sockets; on other operating systems, it also works for other file types (in particular, on Unix, it works on pipes). It cannot be used on regular files to deter...
by gamexg - Python文档中心 - 2008-10-10 19:43:36 阅读(2564) 回复(0)
请问python中,操作mysql,通过执行select * from dd,返回的数据是多少列 (不是多少行),如何知道?
1.使用select实现非阻塞socket # -*- coding: cp936 -*- """ 非阻塞socket的使用(此程序在ubuntu linux和windows xp上测试,Windows可以支持select.select) 监控socket的三个list:in/out/err 程序以5000ms的时间长度为间隔,如果有客户端的请求,接收连接并进行显示;如果没有的话, 每隔5000ms显示一次"no data coming" """ import socket,select host = "" port = 50000 s = socket.socket(socket.AF_INET,socket.SOCK_STREAM...
Cursor attributes rowcount Number of rows affected by the last executed statement, or -1 if no statement was executed or the number can not be determined. InformixDB only provides values for DELETE, UPDATE, and INSERT statements. 好像没有直接的 这个必须遍历一遍结果,++一个变量得到吗
Quite often when you’re writing Linux applications, you may need to examine the state of a number of inputs to determine the next action to take. For example, a communication program such as a terminal emulator needs to read the keyboard and the serial port effectively at the same time. In a single-user system, it might be acceptable to run in a “busy wait” loop, repeatedly scanning the input f...
void fun() { int i; int ch; struct timeval timeout; timeout.tv_sec=1; timeout.tv_usec=0; fd_set readfds; FD_ZERO(&readfds); FD_SET(0,&readfds); i=select(1,&readfds,NULL,NULL,&timeout); if(i==1) ch=getchar(); printf("%c",ch); fun(); } int main() { pid_t pid; if((pid=vfork())==0)fun(); while(1); return 1; } ------------------------- 我原是想通过fun来监听键...
一、winsock中 #include 原型 int select( int nfds , fd_set* readfds , fd_set* writefds , fd_set* exceptfds , const struct timeval* timeout ); nfds:本参数忽略,仅起到兼容作用。 readfds:(可选)指针,指向一组等待可读性检查的套接口。 writefds:(可选)指针,指向一组等待可写性检查的套接口。 exceptfds:(可选)指针,指向一组等待错误检查的套接口。 timeout:select()最多等待时间,对...
select tid FROM `join` group by tid order by count(*) desc limit 2; CREATE TABLE `join` ( `id` int(25) NOT NULL auto_increment, `uid` int(25) NOT NULL, `tid` int(25) NOT NULL, PRIMARY KEY (`id`) ) ENGINE=InnoDB DEFAULT CHARSET=utf8 AUTO_INCREMENT=7 ; -- -- 导出表中的数据 `join` -- INSERT INTO `join` VALUES (1, 1, 1); INSERT INTO `join` VALUES (2, 1, 2); INSERT INTO `join` VALUES (3, 2, ...
select系统调用是用来让我们的程序监视多个文件句柄(file descrīptor)的状态变化的。程序会停在select这里等待,直到被监视的文件句柄有某一个或多个发生了状态改变。 文件在句柄在Linux里很多,如果你man某个函数,在函数返回值部分说到成功后有一个文件句柄被创建的都是的,如man socket可以看到“On success, a file descrīptor for the new socket is returned.”而man 2 open可以看到“open() and creat() return the new f...
获得下拉框中被选中的值 var monthvalue = document.form1.month.options[document.form1.month.selectedIndex].text; alert(monthvalue); } --> 月份: ---------- 01 02 03 04 本文来自ChinaUnix博客,如果查看原文请点:http://blog.chinaunix.net/u1/37105/showart_312646.html
一个UDP的CLIENT,循环向SERVER发数据。发送一次后,就要停下来,等待SERVER给它一个回复,或者超时没有接到SERVER的回复,才进行下一次发送。 要求:用select实现。 不知如何写,大家给个代码。