NP 作業3

Netkitty, or nk (Just like netcat)
Please refer to netcat to see what to implement.

Basic requirements

1. Read from standard input and write to standard output, and transfer the data like netcat does. (35%)
2. Execute a program on a remote machine. A user can input parameters for a program if needed, and can see the execution output. (i.e., a remots shell) (50%)
3. Implement as many as Netcat can do (e.g., supporting more command options). Add 5% for each new function.

Due date: May 22 → 28
Additional hints
use ‘getopt’ for command parsing (see getopt(3))

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說要像netcat，那直接執行摳不摳亦咧豬腳大人~？(歪頭裝口愛)

NP作業2

homework2 作業題目

In this homework, you will write a pair of Little Messenger client and server. The requirements of the Messenger system is as follows.

1. The Messenger client operates in dual modes: command mode and chatting mode. (10%)
2. A user can register a new account from the Messenger client on line, and log in on the Messenger server. (20%)
3. The user can list on-line users on the server.(10%)

4. A user can send messages to another on-line user, or start a conversation with him or her.(20%)

5. A user can broadcast a message to all on-line users. (10%)
6. A user can leave a off-line message to another, and he/she can see the off-line message when he/she logs in.(10%)
7. A user can log out the server. (5%)
8. Add 5 points for each new function.

You do not have to design a GUI like Live Messenger. A text-mode interface is pretty fine. The server can be on an arbitrary port. Due date: Apr. 29.


note:

gcc -o


(ca)

工作站> setenv LC_ALL zh_TW.UTF-8
把目前連線全部的編碼方式都改成UTF-8

[抓蟲中]
以下是流程圖，一樣是用office2010 power point快取圖樣拉的。









參考資料：

1. The World of select()
http://www.lowtek.com/sockets/select.html

> So one main advantage of using select() is that your server will only require a single process to handle all requests. Thus, your server will not need shared memory or synchronization primitives for different 'tasks' to communicate.
> ya!! 一個process!! no more fork!!


2. 
unpv13e/
select/strcliselect01.c
select/strcliselect02.c
tcpcliserv/tcpservselect01.c
tcpcliserv/tcpservpoll01.c


3. Socket Client Examples
 http://www.tutorialspoint.com/unix_sockets/socket_client_example.htm

4. gcc 語法
http://aikosenoo.pixnet.net/blog/post/23038692

30÷2(2+3)÷5=?

這是個語意解讀上的問題(1s)

啊講詳細點就是人和電腦對係數的處理方式不太統一。
而且人類在計算時，下意識進行的大量省去和結合等等都是電腦不懂得，電腦的優點只在於學會了之後很快而已(噴笑)


國小老師教我們
step1. 2+3 replace 5 括號優先
step2. 2(5) replace 10 係數優先
step3. 30÷10 replace 3 左結合
step4. 3÷5 replace 0.6 為最終解

如果電腦要達到這種解讀的話
必須在處理係數的時候，是用刮號以及乘號去取代：2(2+3) replace (2*(2+3))

另一個可能出現的解答15的原因在於係數只用乘法取代，原式變成30÷2*5÷5。

step1. 2 replace 2*
step2. (2+3) replace 5
step3. 30÷2 replace 15
step4. 15*5 replace 75
step5. 75÷5 replace 15

不過這很明顯不是使用者期望的....不過這邊，如朋友所言，這裡已經不是 syntax 的問題而是 semantics的問題啦XDDD


括號跟分數的簡化最好是每做完一步都check一下，這個check是自然演算法中的[下意識]，但是電腦很笨(真正厲害的是工程師─請支持正版)，所以你不寫一串不太直覺的處理沒辦法達到自然運算的效果。

至於/跟÷這兩個傢伙，在自然語言中的語意更是天差地遠。

A/B 解讀為分數，是用橫式表示直式的寫法。(...很令人頭暈齁...沒關係稱下去你就得到它了!!!)

A÷B 解讀為A除以B

雖然現在看起來一樣，但是丟到更長的式子裡去就很可怕了。

以下的ABCD為代數

手寫的 A/BC/D，是先解讀/號並自動加上刮號，是表示((A÷B)*(C÷D))，答案寫成AC/BD

但是(在某種不可能發生在人類自然解讀的情形下)

電腦對於A/BC/D解讀順序是先把B視為C的係數，(A/(B*C))/D，答案是A/BCD。

我compiler修得亂七八糟的，那些專有名詞都忘記系蝦毀惹。

NP作業1

因為沒有閒置機器可供玩轉，所以先安裝虛擬機器
(以下說明網頁來自重灌狂人)

一、在主電腦安裝VirtualBox軟體

二、在VirtualBox建立新的虛擬電腦

三、建立新的虛擬硬碟機

四、選定開機光碟機

五、啟動虛擬電腦、安裝作業系統

六、安裝好系統，更新VirtualBox專屬驅動程式

當然5.6那兩點跟作業需求的Unix-like不一樣。

應用OS fedora，google後就有關網可供下載iso。

虛擬光碟軟體：http://www.daemon-tools.cc/eng/home 我只裝了lite，其他功能用不到。


接下來作業要求

homework01 作業題目

In this homework, you will write a simple Web server with C/C++ in the UNIX environment. The specification of this Web server is as follows:

1. The Web server can be accessed from one of the GUI-based Web browsers, such as IE, Firefox, etc. (40%)

(還好是一個就OK....)

2. The user can access an HTML file on the server on the Web browser. (20%)

3. The user can access a picture (in the format of JPEG or GIF, etc.) from the Web browser. (15%)

4. The Web server can handle zombie processes well.(10%)

5. Add 5 points for each new function (access control, support more data types, ...)

Your Web server will listen on port 80 if possible (but not required). Please upload your report (in one or two pages) in PDF format to e-course by 4/6, and demonstrate your program to the TAs in that week.



同學提供參考網址: http://www.jbox.dk/sanos/webserver.htm

fedora沒有內建vim，這怎麼可以呢!!

要先切到admin account才可以安裝。

Fedora 14 root登入方法→http://mypaper.pchome.com.tw/kisgccc/post/1321808888

要改兩個檔案不要忘記了~

如何在Fedora中安裝vim → http://hi.baidu.com/xuehuo_0411/blog/item/f34197968c49287d54fb9652.html

yum install vim

也不要忘記安裝gcc....



[完成]
以下是用office2010 power point快取圖樣做的流程圖

Big-oh 和 master method

這是今天補習時一直困擾我的兩樣東西

所以乾脆就把東西查查寫寫，以造福後人。

是說如果你不去看英文wiki反而來我這個部落格大概也是走投無路了，那我也就不害羞把有點白癡的想法寫下來了。

補一個還滿詳細的Bog-Oh相關網頁 http://www.cyut.edu.tw/~ckhung/b/al/asympt.php
排版有點不親民不過也只有這個毛病了

關於矩陣那麼點兒事

用 **array取代array[MAX][MAX]的好處不只有大小可以自己指定

除了降低閱讀性稍微降低這個缺點外

在各個thread中傳遞一個矩陣的指標比傳遞整個陣列本身來的容易

缺點就是邊界限制不夠強…

ex:

在main中使用

int **ary;
ary = malloc((MAX+1)*sizeof(*ary));
for(i=0;i<=MAX;i++)
{ary[i]=malloc((MAX+1)*sizeof(**ary));    }

你在thread的地方就可以直接

void subForThread(int *ary)
…
if(*(ary+j) > *(ary+j+1))
{
temp =*(ary+j);
*(ary+j)=*(ary+j+1);
*(ary+j+1)=temp;
}

OS

※ 引述《ch890333 (紅狼)》之銘言：
> Typically, at the completion of a device I/O, a single interrupt is raised
> and appropriately handled by the host processor. In certain settings,96
> however, the code that is to be executed at the completion of the I/O
> can be broken into two separate pieces, one of which executes imme-
> diately after the I/O completes and schedules a second interrupt for
> the remaining piece of code to be executed at a later time. What is the
> purpose of using this strategy in the design of interrupt handlers?


The purpose of this strategy is to ensure that the most critical
aspect of the interrupt handling code is performed first and the less
critical portions of the code is delayed for the future.

這種兩截式策略是為了確保中斷重要的部份可以先被執行，不那麼重要的部份可以稍晚執行。

For instance, when a device finishes an I/O operation, the device control
operations corresponding to declaring the device as no longer being busy are
more important in order to issue future operations.

像是一個裝置完成IO後，會馬上發表相對聲明︰『我很閒!!!』以表明未來可以接受排程。

However, the task of copying the data provided by the device to the
appropriate user or kernel memory regions can be delayed for a future
point when the CPU is idle.


不過，像是把IO動作所copy的內容顯示給使用者或塞進kernel記憶體這些事情就可以讓CPU在未來有空的時候再做。

In such a scenario, a latter lower priority interrupt handler is used to perform the copy operation.

在這種情況下，(比基尼…我是說兩截式通知的)下半截/延遲/沒那麼重要的通知就會被運用在copy操作中。


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快來人找我去翻譯課本!!