fifo | 易学教程

FIFO Implementation in Inventory using SQL

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问题 This is basically an inventory project which tracks the "Stock In" and "Stock Out" of items through Purchase and sales respectively. The inventory system follows FIFO Method (the items which are first purchased are always sold first). For example: If we purchased Item A in months January, February and March When a customer comes we give away items purchased during January only when the January items are over we starts giving away February items and so on So I have to show here the total stock

How to set FIFO and palindrome compare?

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问题 I have this windows application 1.- So, first when I Add a number it added to listbox1 but not to list 2. I need to be add ed to listo 2 to 2.- I need the numbers be added separately... For example if I add number 202, it split on 2 after 0 after 2 3.- I need add button for FIFO, but I don't know how can I program it. 4.-Finally compare one by one it with listbox1 with listbox2 with polindrome method, and if its palindrome show message box, say "they are polindrome", if not, say "number it's

How does a parent process read a FIFO after the child process finished the writing that FIFO?

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问题 I have a very simple basic program that has two process first one is parent and second one is child . Child process should write some stuff to the FIFO . After all writing jobs finished(after the child is terminated). Then parent process should read all the FIFO file and print to the stdout . So I think, I need a wait(NULL); for parent . So the parent will wait until the child is terminated. But child is also blocked because of the writing and blocked for reading this writes. So both process

栈方法 LIFO - 队方法 FIFO

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1、栈方法 LIFO(Last-In-First-Out,后进先出)最新添加最早被移除。栈中项的插入（叫做推入）和移除（叫做弹出）只发生在一个位置---桟的顶部。模拟：push()方式可以接收任意数量参数，它逐个添加到数组末尾，并修改数组长度。pop()方法从数组末端最后一项，并减少length var colors = new Array(); //创建一个数组 var count = colors.push('red','green'); // count -> 2 colors -> ["red", "green"] count = colors.push('black'); // count -> 3 colors -> ["red", "green","black"] var item = colors.pop(); //"black" length -> 2 2、队方法 FIFO(First-In-First-Out,先进先出) 队列在列表末端添加项，从列表的前端移除项模拟:push()方式可以接收任意数量参数，它逐个添加到数组末尾，并修改数组长度。shift()移除数组第一项并返回该项，并length-1 var colors = new Array(); //创建一个数组 var count = colors.push("red", "green"); /

2019年8月9日星期五（系统编程）

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2019 年 8 月 9 日星期五一 . linux 多进程编程 - 通信方式。 1. 为什么进程之间要进行数据通信？例子： ./test -> 开启一个名字为 test的进程。 ./project -> 开启一个名字为 project的进程。通过学习通信方式，使得不同进程之间进行数据交换，例如 test进程发送数据给 project进程，从而控制 project进程运行状态。 2. 在 linux 下，通信方式有哪些？各自有什么特点？以下几种方式属于系统编程的通信方式，只能同一台主机内部进程通信，不能跨主机。 1 ）管道通信管道通信分为有名管道与无名管道通信，管道也是 linux的一种特殊文件，进程可以写入数据到管道中，从而实现通信。 2 ）信号在 linux下，有非常多信号，例如暂停，继续，停止 ...，某一个进程通过发送信号给另外一个进程，从进行通信。 3 ）消息队列消息队列可以读取另外一个进程发送来的数据，而且可以读取特定的数据。 4 ）共享内存多个进程同时访问同一片内存空间。能够跨主机通信的，只有网络编程才能实现。 1 ）套接字编程可以实现不同的主机之间的通信。二 . 进程之间通信 - 无名管道 1. 什么是无名管道？作用机制如何？无名管道只能作用于亲缘关系的进程，例如父子进程。无名管道其实是数组来的，里面有读端与写端，进程只需要将数据写入

Linux select() and FIFO ordering of multiple sockets?

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问题 Is there any way for the Linux select() call relay event ordering? A description of what I'm seeing: On one machine, I wrote a simple program which sends three multicast packets, one to each of three different multicast groups. These packets are sent back-to-back, with no delay in between. I.e. sendto(mcast_group1); sendto(mcast_group2); sendto(mcast_group3). On the other machine, I have a receiving program. The program uses one socket per multicast group. Each socket does a bind() and IP_ADD

how 2 c++ programs call each other's class/functions on same linux box?

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问题 I'm brand new to c++, so my vocab's probably off. I currently make 100% ajax sites but want to work in websockets to autoupdate relevant clients. I'm using fastcgi++ and websocket++. I'd like to serve all data via the websocket but update the database via ajax calls. My problem comes in when I want to have the ajax page trigger the websocket. I've read about sockets, fifo, and pipes, but I'm not sure which one is ideal for this situation. For two c++ programs, one ajax & one websocket, on the

Running mpg123 with FIFO control?

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问题 I need to run mpg123 with a single file, such that it will autostart and autoclose, like it normally does, however, I need to be able to override this default behavior with commands sent to a fifo file. I had been running mpg123 filename.mp3 from a script, and simply waiting for it to finish before moving on. However, I'd like another script to be able to pause playback, control volume, or kill the process early, depending on the user's input. mpg123 -R --fifo /srv/http/newsctl filename.mp3

RT-Thread USB虚拟串口收发调试

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学习过程中参考博文：记录——基于 RT-Thread 实现 USB 虚拟串口但是遇到了两个问题： 1.串口有设备，但是不能发送； 2.串口能发送但不能接收；第一个问题，是因为rtt的usb虚拟串口默认启用了RTS和DTR（终端准备好接收）: static rt_err_t _interface_handler ( ufunction_t func , ureq_t setup ) { struct vcom * data ; RT_ASSERT ( func != RT_NULL ) ; RT_ASSERT ( func -> device != RT_NULL ) ; RT_ASSERT ( setup != RT_NULL ) ; data = ( struct vcom * ) func -> user_data ; switch ( setup -> bRequest ) { case CDC_SEND_ENCAPSULATED_COMMAND : break ; case CDC_GET_ENCAPSULATED_RESPONSE : break ; case CDC_SET_COMM_FEATURE : break ; case CDC_GET_COMM_FEATURE : break ; case CDC_CLEAR_COMM_FEATURE : break ;

Maintaining a FIFO readable across different executions

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问题 I've never used a named pipe before and recently realized that is just what I need. I'm running a program using gnu parallel which could produce tons (GB's to 1TB, hard to know right now) of output formatted for a data base on mySQL. I figured out that I can open two terminals: Terminal 1 gets something like: find . -type f -name "*.h" | parallel --jobs 12 'cprogram {}' > /home/pipe Where pipe is a fifo made with mkfifo . On a second terminal, I run a command similar to this: mysql