C#－阿尼｜痞客邦

目前分類：C# (4)

瀏覽方式：標題列表簡短摘要

Jul 09 Fri 2010 21:49
計算 Byte 數量

最近有個格式化字串的需求，是要計算已知字串的 Byte 數量，每 100 個 Byte 加上一個換行符號(不能超過100)。一開始的想法是一個 char 一個 char 去跑迴圈並計算 Byte 數。不過這樣又似乎不太妥當，想來想去，最後寫成這個樣子：

public static string SetupType(string text) {
    //先去除換行字元
    text = text.Replace("\r", "").Replace("\n", "");

    //每行最大 Byte 數
    int bytesCountEachLine = 100;

    //記錄目前已處理完成的字元數
    int charIndex = 0;

    //最後的回傳值
    string result = string.Empty;

    Encoding ansi = Encoding.Default;
    byte[] textBytes = ansi.GetBytes(text);

    while (charIndex < text.Length) {
        //起始位置
        int start = ansi.GetByteCount(text.Substring(0, charIndex)) ;

        //利用 Encoding.GetCharCount 從起始位置將 100 個 Bytes 的字元一次取出
        int count = 0;

        if (textBytes.Length - start > bytesCountEachLine)
            count = ansi.GetCharCount(textBytes, start, bytesCountEachLine);
        else
            count = ansi.GetCharCount(textBytes, start, textBytes.Length - start);

        string target = text.Substring(charIndex, count);

        //取出來的字串可能會大於 100 Bytes，所以需要把多餘的去掉
        while (ansi.GetByteCount(target) > bytesCountEachLine) {
            target = target.Substring(0, target.Length - 1);
            count -= 1;
        }

        charIndex += count;


        //最後一行不用加斷行符號
        if (charIndex < text.Length)
            result += target + "\r\n";
        else
            result += target;
    }

    return result;
}

用一段以前很愛看的小說片段來測試，結果如下：

測試前：

測試後：

AnferneeHardaway 發表在痞客邦留言(0) 人氣()

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Jun 29 Tue 2010 23:26
改寫字串

剛剛看到天才少年 laneser 寫了一段程式碼，為方便說明，我稍微刪掉了一些。大致上如下：

[STAThread]
static unsafe void Main() {
    string s = "123";
    
    fixed (char* ps = s) {
        ps[0] = '3';
        ps[1] = '2';
        ps[2] = '1';
    }

    MessageBox.Show("123");
}

得到的結果是這樣

呵~很有趣吧！其實原理不難，主要是因為 .NET 的 String 型別是不可變動的 (Immutable)，因此為了節省記憶體的使用，CLR 會建立一個保留集區 (Intern Pool) 來存放字串。當程式中使用字串時，CLR會先檢查保留集區，有的話就傳回保留集區內的參考；沒有的話，就把字串加到保留集區內，再傳回參考。

所以上述程式碼其實是這樣執行的：

天才少年的這段程式碼實在太有趣了！

AnferneeHardaway 發表在痞客邦留言(1) 人氣()

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Feb 25 Thu 2010 16:43
Punycode

網友問了個問題，我天真的認為是UrlEncode()就可以解決，直到心冷大指點後，才知道事情不是我想的那麼簡單。經過測試後，不管用什麼方法都沒辦法正確的用WebClient去抓資料，google了老半天也找不到有用的資訊。結果無意中發現這篇，看來跟這個名為punycode的東西有關，有了關鍵字，呵~~人生就變彩色的了，一下子就找到有用的文章。

看起來是因為大多數的 DNS 伺服器僅支援 ASCII 字元，所以用中文字下去解析時就會發生錯誤，因此才出現punycode這個東西。以下是google到的解法

1.自己將中文轉成punycode

public partial class Form1 : Form {

    public Form1() {

        InitializeComponent();

    }

  

    private void Form1_Load(object sender, EventArgs e) {

        string strPunycode = "http://xn--" + Punycode.encode("正負2度c") + ".tw/";

        WebClient client = new WebClient();

        string html = client.DownloadString(strPunycode);

    }

}

  

class Punycode {

    /* Punycode parameters */

    static int TMIN = 1;

    static int TMAX = 26;

    static int BASE = 36;

    static int INITIAL_N = 128;

    static int INITIAL_BIAS = 72;

    static int DAMP = 700;

    static int SKEW = 38;

    static char DELIMITER = '-';

    /**

     * Punycodes a unicode string.

     *

     * @param input Unicode string.

     * @return Punycoded string.

     */

    public static String encode(String input) {

        int n = INITIAL_N;

        int delta = 0;

        int bias = INITIAL_BIAS;

        StringBuilder output = new StringBuilder();

        // Copy all basic code points to the output

        int b = 0;

        for (int i = 0; i < input.Length; i++) {

            char c = input[i];

            if (isBasic(c)) {

                output.Append(c);

                b++;

            }

        }

        // Append delimiter

        if (b > 0) {

            output.Append(DELIMITER);

        }

        int h = b;

        while (h < input.Length) {

            int m = int.MaxValue;

            // Find the minimum code point >= n

            for (int i = 0; i < input.Length; i++) {

                int c = input[i];

                if (c >= n && c < m) {

                    m = c;

                }

            }

            if (m - n > (int.MaxValue - delta) / (h + 1)) {

                throw new Exception("OVERFLOW");

            }

            delta = delta + (m - n) * (h + 1);

            n = m;

            for (int j = 0; j < input.Length; j++) {

                int c = input[j];

                if (c < n) {

                    delta++;

                    if (0 == delta) {

                        throw new Exception("OVERFLOW");

                    }

                }

                if (c == n) {

                    int q = delta;

                    for (int k = BASE; ; k += BASE) {

                        int t;

                        if (k <= bias) {

                            t = TMIN;

                        } else if (k >= bias + TMAX) {

                            t = TMAX;

                        } else {

                            t = k - bias;

                        }

                        if (q < t) {

                            break;

                        }

                        output.Append((char)digit2codepoint(t + (q - t) % (BASE - t)));

                        q = (q - t) / (BASE - t);

                    }

                    output.Append((char)digit2codepoint(q));

                    bias = adapt(delta, h + 1, h == b);

                    delta = 0;

                    h++;

                }

            }

            delta++;

            n++;

        }

        return output.ToString();

    }

    /**

     * Decode a punycoded string.

     *

     * @param input Punycode string

     * @return Unicode string.

     */

    public static String decode(String input) {

        int n = INITIAL_N;

        int i = 0;

        int bias = INITIAL_BIAS;

        StringBuilder output = new StringBuilder();

        int d = input.LastIndexOf(DELIMITER);

        if (d > 0) {

            for (int j = 0; j < d; j++) {

                char c = input[j];

                if (!isBasic(c)) {

                    throw new Exception("BAD_INPUT");

                }

                output.Append(c);

            }

            d++;

        } else {

            d = 0;

        }

        while (d < input.Length) {

            int oldi = i;

            int w = 1;

            for (int k = BASE; ; k += BASE) {

                if (d == input.Length) {

                    throw new Exception("BAD_INPUT");

                }

                int c = input[d++];

                int digit = codepoint2digit(c);

                if (digit > (int.MaxValue - i) / w) {

                    throw new Exception("OVERFLOW");

                }

                i = i + digit * w;

                int t;

                if (k <= bias) {

                    t = TMIN;

                } else if (k >= bias + TMAX) {

                    t = TMAX;

                } else {

                    t = k - bias;

                }

                if (digit < t) {

                    break;

                }

                w = w * (BASE - t);

            }

            bias = adapt(i - oldi, output.Length + 1, oldi == 0);

            if (i / (output.Length + 1) > int.MaxValue - n) {

                throw new Exception("OVERFLOW");

            }

            n = n + i / (output.Length + 1);

            i = i % (output.Length + 1);

            output.Insert(i, (char)n);

            i++;

        }

        return output.ToString();

    }

    public static int adapt(int delta, int numpoints, bool first) {

        if (first) {

            delta = delta / DAMP;

        } else {

            delta = delta / 2;

        }

        delta = delta + (delta / numpoints);

        int k = 0;

        while (delta > ((BASE - TMIN) * TMAX) / 2) {

            delta = delta / (BASE - TMIN);

            k = k + BASE;

        }

        return k + ((BASE - TMIN + 1) * delta) / (delta + SKEW);

    }

    public static bool isBasic(char c) {

        return c < 0x80;

    }

    public static int digit2codepoint(int d) {

        if (d < 26) {

            // 0..25 : 'a'..'z'

            return d + 'a';

        } else if (d < 36) {

            // 26..35 : '0'..'9';

            return d - 26 + '0';

        } else {

            throw new Exception("BAD_INPUT");

        }

    }

    public static int codepoint2digit(int c) {

        if (c - '0' < 10) {

            // '0'..'9' : 26..35

            return c - '0' + 26;

        } else if (c - 'a' < 26) {

            // 'a'..'z' : 0..25

            return c - 'a';

        } else {

            throw new Exception("BAD_INPUT");

        }

    }

}

2.直接使用config檔的設定

．在C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\CONFIG\machine.config加入這一段

   1: <section name="uri" type="System.Configuration.UriSection, System, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" />

．在app.config中加入

<configuration>

  <uri>

  <idn enabled="All" />

  <iriParsing enabled="true" />

  </uri>

</configuration>

然後程式碼完全不用動

public partial class Form1 : Form {

    public Form1() {

        InitializeComponent();

    }

  

    private void Form1_Load(object sender, EventArgs e) {

        string url = "http://正負2度c.tw/";

        WebClient client = new WebClient();

        string html = client.DownloadString(url);

    }

}

以上就屬第二種最方便，也說明了.NET真的是好用到一個不行啊~~

AnferneeHardaway 發表在痞客邦留言(0) 人氣()

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Dec 18 Fri 2009 22:27
Copy Properties

同事問了一個問題：

假如有兩個物件(A和B)，這兩個物件分屬不同類別，且大多數的屬性都一樣，但彼此沒有繼承關係，也不能修改原始類別的程式碼。要如何快速將物件A的屬性值全部複製給物件B？？

思考了一下，由於功力不深，所以只想得出PropertyInfo類別。

首先定義ClassA及ClassB

public class ClassA {

    public string Str1 { get; set; }

    public string Str2 { get; set; }

    public string Str3 { get; set; }

    public string Str4 { get; set; }

    public string Str5 { get; set; }

    public string Str6 { get; set; }

    public string Str7 { get; set; }

    public string Str8 { get; set; }

    public string Str9 { get; set; }

    public string Str10 { get; set; }

    public string Str11 { get; set; }

    public string Str12 { get; set; }

    public string Str13 { get; set; }

    public string Str14 { get; set; }

    public string Str15 { get; set; }

    public string Str16 { get; set; }

    public string Str17 { get; set; }

    public string Str18 { get; set; }

    public string Str19 { get; set; }

    public string Str20 { get; set; }

    public string Str21 { get; set; }

    public string Str22 { get; set; }

    public string Str23 { get; set; }

    public string Str24 { get; set; }

    public string Str25 { get; set; }

    public string Str26 { get; set; }

    public string Str27 { get; set; }

    public string Str28 { get; set; }

    public string Str29 { get; set; }

    public string Str30 { get; set; }

    public string Str31 { get; set; }

    public string Str32 { get; set; }

    public string Str33 { get; set; }

    public string Str34 { get; set; }

    public string Str35 { get; set; }

    public string Str36 { get; set; }

    public string Str37 { get; set; }

    public string Str38 { get; set; }

    public string Str39 { get; set; }

    public string Str40 { get; set; }

    public string Str41 { get; set; }

    public string Str42 { get; set; }

    public string Str43 { get; set; }

    public string Str44 { get; set; }

    public string Str45 { get; set; }

    public string Str46 { get; set; }

    public string Str47 { get; set; }

    public string Str48 { get; set; }

    public string Str49 { get; set; }

    public string Str50 { get; set; }

    public string Str51 { get; set; }

    public string Str52 { get; set; }

    public string Str53 { get; set; }

    public string Str54 { get; set; }

    public string Str55 { get; set; }

    public string Str56 { get; set; }

    public string Str57 { get; set; }

    public string Str58 { get; set; }

    public string Str59 { get; set; }

    public string Str60 { get; set; }

    public string Str61 { get; set; }

    public string Str62 { get; set; }

    public string Str63 { get; set; }

    public string Str64 { get; set; }

    public string Str65 { get; set; }

    public string Str66 { get; set; }

    public string Str67 { get; set; }

    public string Str68 { get; set; }

    public string Str69 { get; set; }

    public string Str70 { get; set; }

    public string Str71 { get; set; }

    public string Str72 { get; set; }

    public string Str73 { get; set; }

    public string Str74 { get; set; }

    public string Str75 { get; set; }

    public string Str76 { get; set; }

    public string Str77 { get; set; }

    public string Str78 { get; set; }

    public string Str79 { get; set; }

    public string Str80 { get; set; }

    public string Str81 { get; set; }

    public string Str82 { get; set; }

    public string Str83 { get; set; }

    public string Str84 { get; set; }

    public string Str85 { get; set; }

    public string Str86 { get; set; }

    public string Str87 { get; set; }

    public string Str88 { get; set; }

    public string Str89 { get; set; }

    public string Str90 { get; set; }

    public string Str91 { get; set; }

    public string Str92 { get; set; }

    public string Str93 { get; set; }

    public string Str94 { get; set; }

    public string Str95 { get; set; }

    public string Str96 { get; set; }

    public string Str97 { get; set; }

    public string Str98 { get; set; }

    public string Str99 { get; set; }

    public string Str100 { get; set; }

}

public class ClassB {

    public string Str1 { get; set; }

    public string Str2 { get; set; }

    public string Str3 { get; set; }

    public string Str4 { get; set; }

    public string Str5 { get; set; }

    public string Str6 { get; set; }

    public string Str7 { get; set; }

    public string Str8 { get; set; }

    public string Str9 { get; set; }

    public string Str10 { get; set; }

    public string Str11 { get; set; }

    public string Str12 { get; set; }

    public string Str13 { get; set; }

    public string Str14 { get; set; }

    public string Str15 { get; set; }

    public string Str16 { get; set; }

    public string Str17 { get; set; }

    public string Str18 { get; set; }

    public string Str19 { get; set; }

    public string Str20 { get; set; }

    public string Str21 { get; set; }

    public string Str22 { get; set; }

    public string Str23 { get; set; }

    public string Str24 { get; set; }

    public string Str25 { get; set; }

    public string Str26 { get; set; }

    public string Str27 { get; set; }

    public string Str28 { get; set; }

    public string Str29 { get; set; }

    public string Str30 { get; set; }

    public string Str31 { get; set; }

    public string Str32 { get; set; }

    public string Str33 { get; set; }

    public string Str34 { get; set; }

    public string Str35 { get; set; }

    public string Str36 { get; set; }

    public string Str37 { get; set; }

    public string Str38 { get; set; }

    public string Str39 { get; set; }

    public string Str40 { get; set; }

    public string Str41 { get; set; }

    public string Str42 { get; set; }

    public string Str43 { get; set; }

    public string Str44 { get; set; }

    public string Str45 { get; set; }

    public string Str46 { get; set; }

    public string Str47 { get; set; }

    public string Str48 { get; set; }

    public string Str49 { get; set; }

    public string Str50 { get; set; }

    public string Str51 { get; set; }

    public string Str52 { get; set; }

    public string Str53 { get; set; }

    public string Str54 { get; set; }

    public string Str55 { get; set; }

    public string Str56 { get; set; }

    public string Str57 { get; set; }

    public string Str58 { get; set; }

    public string Str59 { get; set; }

    public string Str60 { get; set; }

    public string Str61 { get; set; }

    public string Str62 { get; set; }

    public string Str63 { get; set; }

    public string Str64 { get; set; }

    public string Str65 { get; set; }

    public string Str66 { get; set; }

    public string Str67 { get; set; }

    public string Str68 { get; set; }

    public string Str69 { get; set; }

    public string Str70 { get; set; }

    public string Str71 { get; set; }

    public string Str72 { get; set; }

    public string Str73 { get; set; }

    public string Str74 { get; set; }

    public string Str75 { get; set; }

    public string Str76 { get; set; }

    public string Str77 { get; set; }

    public string Str78 { get; set; }

    public string Str79 { get; set; }

    public string Str80 { get; set; }

    public string Str81 { get; set; }

    public string Str82 { get; set; }

    public string Str83 { get; set; }

    public string Str84 { get; set; }

    public string Str85 { get; set; }

    public string Str86 { get; set; }

    public string Str87 { get; set; }

    public string Str88 { get; set; }

    public string Str89 { get; set; }

    public string Str90 { get; set; }

    public int Str91 { get; set; }

    public int Str92 { get; set; }

    public int Str93 { get; set; }

    public int Str94 { get; set; }

    public int Str95 { get; set; }

    public int Str96 { get; set; }

    public int Str97 { get; set; }

    public int Str98 { get; set; }

    public int Str99 { get; set; }

    public int Str100 { get; set; }

}

接著產生物件A、物件B

ClassA a = new ClassA() {

            Str1 = "Str1",

            Str2 = "Str2",

            Str3 = "Str3",

            Str4 = "Str4",

            Str5 = "Str5",

            Str6 = "Str6",

            Str7 = "Str7",

            Str8 = "Str8",

            Str9 = "Str9",

            Str10 = "Str10",

            Str11 = "Str11",

            Str12 = "Str12",

            Str13 = "Str13",

            Str14 = "Str14",

            Str15 = "Str15",

            Str16 = "Str16",

            Str17 = "Str17",

            Str18 = "Str18",

            Str19 = "Str19",

            Str20 = "Str20",

            Str21 = "Str21",

            Str22 = "Str22",

            Str23 = "Str23",

            Str24 = "Str24",

            Str25 = "Str25",

            Str26 = "Str26",

            Str27 = "Str27",

            Str28 = "Str28",

            Str29 = "Str29",

            Str30 = "Str30",

            Str31 = "Str31",

            Str32 = "Str32",

            Str33 = "Str33",

            Str34 = "Str34",

            Str35 = "Str35",

            Str36 = "Str36",

            Str37 = "Str37",

            Str38 = "Str38",

            Str39 = "Str39",

            Str40 = "Str40",

            Str41 = "Str41",

            Str42 = "Str42",

            Str43 = "Str43",

            Str44 = "Str44",

            Str45 = "Str45",

            Str46 = "Str46",

            Str47 = "Str47",

            Str48 = "Str48",

            Str49 = "Str49",

            Str50 = "Str50",

            Str51 = "Str51",

            Str52 = "Str52",

            Str53 = "Str53",

            Str54 = "Str54",

            Str55 = "Str55",

            Str56 = "Str56",

            Str57 = "Str57",

            Str58 = "Str58",

            Str59 = "Str59",

            Str60 = "Str60",

            Str61 = "Str61",

            Str62 = "Str62",

            Str63 = "Str63",

            Str64 = "Str64",

            Str65 = "Str65",

            Str66 = "Str66",

            Str67 = "Str67",

            Str68 = "Str68",

            Str69 = "Str69",

            Str70 = "Str70",

            Str71 = "Str71",

            Str72 = "Str72",

            Str73 = "Str73",

            Str74 = "Str74",

            Str75 = "Str75",

            Str76 = "Str76",

            Str77 = "Str77",

            Str78 = "Str78",

            Str79 = "Str79",

            Str80 = "Str80",

            Str81 = "Str81",

            Str82 = "Str82",

            Str83 = "Str83",

            Str84 = "Str84",

            Str85 = "Str85",

            Str86 = "Str86",

            Str87 = "Str87",

            Str88 = "Str88",

            Str89 = "Str89",

            Str90 = "Str90",

            Str91 = "Str91",

            Str92 = "Str92",

            Str93 = "Str93",

            Str94 = "Str94",

            Str95 = "Str95",

            Str96 = "Str96",

            Str97 = "Str97",

            Str98 = "Str98",

            Str99 = "Str99",

            Str100 = "Str100"

        };

        ClassB b = new ClassB();

最後就是複製的動作了

Type typeB = typeof(ClassB);

PropertyInfo[] propertiesA = typeof(ClassA).GetProperties(BindingFlags.Public | BindingFlags.Instance);

foreach (PropertyInfo infoA in propertiesA) {

    string name = infoA.Name;

    PropertyInfo infoB = typeB.GetProperty(name, BindingFlags.Public | BindingFlags.Instance);

    if (infoB != null && infoA.PropertyType == infoB.PropertyType) {

        infoB.SetValue(b, infoA.GetValue(a, null), null);

    }

}