这些有用吗?

public static bool CoinToss(this Random rng)
{
    return rng.Next(2) == 0;
}

public static T OneOf<T>(this Random rng, params T[] things)
{
    return things[rng.Next(things.Length)];
}

Random rand;
bool luckyDay = rand.CoinToss();
string babyName = rand.OneOf("John", "George", "Radio XBR74 ROCKS!");

我在我的web项目中使用这些，主要是MVC。我为ViewData和TempData写了一些这样的代码

/// <summary>
/// Checks the Request.QueryString for the specified value and returns it, if none 
/// is found then the default value is returned instead
/// </summary>
public static T QueryValue<T>(this HtmlHelper helper, string param, T defaultValue) {
    object value = HttpContext.Current.Request.QueryString[param] as object;
    if (value == null) { return defaultValue; }
    try {
        return (T)Convert.ChangeType(value, typeof(T));
    } catch (Exception) {
        return defaultValue;
    }
}

这样我就可以写……

<% if (Html.QueryValue("login", false)) { %>
    <div>Welcome Back!</div>

<% } else { %>
    <%-- Render the control or something --%>

<% } %>

python字典方法:

/// <summary>
/// If a key exists in a dictionary, return its value, 
/// otherwise return the default value for that type.
/// </summary>
public static U GetWithDefault<T, U>(this Dictionary<T, U> dict, T key)
{
    return dict.GetWithDefault(key, default(U));
}

/// <summary>
/// If a key exists in a dictionary, return its value,
/// otherwise return the provided default value.
/// </summary>
public static U GetWithDefault<T, U>(this Dictionary<T, U> dict, T key, U defaultValue)
{
    return dict.ContainsKey(key)
        ? dict[key]
        : defaultValue;
}

当您希望将时间戳附加到文件名以确保唯一性时非常有用。

/// <summary>
/// Format a DateTime as a string that contains no characters
//// that are banned from filenames, such as ':'.
/// </summary>
/// <returns>YYYY-MM-DD_HH.MM.SS</returns>
public static string ToFilenameString(this DateTime dt)
{
    return dt.ToString("s").Replace(":", ".").Replace('T', '_');
}

无论如何，把它放在codeplex项目中。

将对象序列化/反序列化为XML:

/// <summary>Serializes an object of type T in to an xml string</summary>
/// <typeparam name="T">Any class type</typeparam>
/// <param name="obj">Object to serialize</param>
/// <returns>A string that represents Xml, empty otherwise</returns>
public static string XmlSerialize<T>(this T obj) where T : class, new()
{
    if (obj == null) throw new ArgumentNullException("obj");

    var serializer = new XmlSerializer(typeof(T));
    using (var writer = new StringWriter())
    {
        serializer.Serialize(writer, obj);
        return writer.ToString();
    }
}

/// <summary>Deserializes an xml string in to an object of Type T</summary>
/// <typeparam name="T">Any class type</typeparam>
/// <param name="xml">Xml as string to deserialize from</param>
/// <returns>A new object of type T is successful, null if failed</returns>
public static T XmlDeserialize<T>(this string xml) where T : class, new()
{
    if (xml == null) throw new ArgumentNullException("xml");

    var serializer = new XmlSerializer(typeof(T));
    using (var reader = new StringReader(xml))
    {
        try { return (T)serializer.Deserialize(reader); }
        catch { return null; } // Could not be deserialized to this type.
    }
}

我有一个扩展方法记录异常:

public static void Log(this Exception obj)
{
  //your logging logic here
}

它的用法是这样的:

try
{
    //Your stuff here
}
catch(Exception ex)
{
    ex.Log();
}

[抱歉发了两次;第二个设计得更好:-)]

我一直在寻找一种方式来回馈社区我所开发的一些东西。

这里有一些FileInfo扩展，我觉得非常有用。

/// <summary>
/// Open with default 'open' program
/// </summary>
/// <param name="value"></param>
public static Process Open(this FileInfo value)
{
    if (!value.Exists)
        throw new FileNotFoundException("File doesn't exist");
    Process p = new Process();
    p.StartInfo.FileName = value.FullName;
    p.StartInfo.Verb = "Open";
    p.Start();
    return p;
}

/// <summary>
/// Print the file
/// </summary>
/// <param name="value"></param>
public static void Print(this FileInfo value)
{
    if (!value.Exists)
        throw new FileNotFoundException("File doesn't exist");
    Process p = new Process();
    p.StartInfo.FileName = value.FullName;
    p.StartInfo.Verb = "Print";
    p.Start();
}

/// <summary>
/// Send this file to the Recycle Bin
/// </summary>
/// <exception cref="File doesn't exist" />
/// <param name="value"></param>
public static void Recycle(this FileInfo value)
{        
    value.Recycle(false);
}

/// <summary>
/// Send this file to the Recycle Bin
/// On show, if person refuses to send file to the recycle bin, 
/// exception is thrown or otherwise delete fails
/// </summary>
/// <exception cref="File doesn't exist" />
/// <exception cref="On show, if user refuses, throws exception 'The operation was canceled.'" />
/// <param name="value">File being recycled</param>
/// <param name="showDialog">true to show pop-up</param>
public static void Recycle(this FileInfo value, bool showDialog)
{
    if (!value.Exists)
            throw new FileNotFoundException("File doesn't exist");
    if( showDialog )
        FileSystem.DeleteFile
            (value.FullName, UIOption.AllDialogs, 
            RecycleOption.SendToRecycleBin);
    else
        FileSystem.DeleteFile
            (value.FullName, UIOption.OnlyErrorDialogs, 
            RecycleOption.SendToRecycleBin);
}

在用户喜欢的编辑器中打开任意文件:

new FileInfo("C:\image.jpg").Open();

打印任何操作系统知道如何打印的文件:

new FileInfo("C:\image.jpg").Print();

将任何文件发送到回收站:

你必须包括微软。VisualBasic参考 使用Microsoft.VisualBasic.FileIO;

例子:

new FileInfo("C:\image.jpg").Recycle();

Or

// let user have a chance to cancel send to recycle bin.
new FileInfo("C:\image.jpg").Recycle(true);