下面是我经常使用的演示格式。

public static string ToTitleCase(this string mText)
{
    if (mText == null) return mText;

    System.Globalization.CultureInfo cultureInfo = System.Threading.Thread.CurrentThread.CurrentCulture;
    System.Globalization.TextInfo textInfo = cultureInfo.TextInfo;

    // TextInfo.ToTitleCase only operates on the string if is all lower case, otherwise it returns the string unchanged.
    return textInfo.ToTitleCase(mText.ToLower());
}

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:-)]

我喜欢下面这些方法来处理带有Flags属性集的枚举:

public static bool AnyOf(this object mask, object flags)
{
    return ((int)mask & (int)flags) != 0;
}
public static bool AllOf(this object mask, object flags)
{
    return ((int)mask & (int)flags) == (int)flags;
}
public static object SetOn(this object mask, object flags)
{
    return (int)mask | (int)flags;
}
etc.

使用示例:

var options = SomeOptions.OptionA;
options = options.SetOn(OptionB);
options = options.SetOn(OptionC);

if (options.AnyOf(SomeOptions.OptionA | SomeOptions.OptionB))
{
etc.

原始方法来自本文:http://www.codeproject.com/KB/cs/masksandflags.aspx?display=Print 我只是把它们转换成扩展方法。

但它们的一个问题是对象类型的参数，这意味着所有对象最终都被这些方法扩展，而理想情况下，它们应该只应用于枚举。

更新 根据评论，你可以绕过“签名污染”，以牺牲性能为代价，如下所示:

public static bool AnyOf(this Enum mask, object flags)
{
    return (Convert.ToInt642(mask) & (int)flags) != 0;
}

HTH。这些是我的一些主要问题。

using System;
using System.Collections.Generic;
using System.Globalization;
using System.Linq;
using System.Text;

namespace Insert.Your.Namespace.Here.Helpers
{
    public static class Extensions
    {
        public static bool IsNullOrEmpty<T>(this IEnumerable<T> iEnumerable)
        {
            // Cheers to Joel Mueller for the bugfix. Was .Count(), now it's .Any()
            return iEnumerable == null ||
                   !iEnumerable.Any();
        }

        public static IList<T> ToListIfNotNullOrEmpty<T>(this IList<T> iList)
        {
            return iList.IsNullOrEmpty() ? null : iList;
        }

        public static PagedList<T> ToPagedListIfNotNullOrEmpty<T>(this PagedList<T> pagedList)
        {
            return pagedList.IsNullOrEmpty() ? null : pagedList;
        }

        public static string ToPluralString(this int value)
        {
            return value == 1 ? string.Empty : "s";
        }

        public static string ToReadableTime(this DateTime value)
        {
            TimeSpan span = DateTime.Now.Subtract(value);
            const string plural = "s";


            if (span.Days > 7)
            {
                return value.ToShortDateString();
            }

            switch (span.Days)
            {
                case 0:
                    switch (span.Hours)
                    {
                        case 0:
                            if (span.Minutes == 0)
                            {
                                return span.Seconds <= 0
                                           ? "now"
                                           : string.Format("{0} second{1} ago",
                                                           span.Seconds,
                                                           span.Seconds != 1 ? plural : string.Empty);
                            }
                            return string.Format("{0} minute{1} ago",
                                                 span.Minutes,
                                                 span.Minutes != 1 ? plural : string.Empty);
                        default:
                            return string.Format("{0} hour{1} ago",
                                                 span.Hours,
                                                 span.Hours != 1 ? plural : string.Empty);
                    }
                default:
                    return string.Format("{0} day{1} ago",
                                         span.Days,
                                         span.Days != 1 ? plural : string.Empty);
            }
        }

        public static string ToShortGuidString(this Guid value)
        {
            return Convert.ToBase64String(value.ToByteArray())
                .Replace("/", "_")
                .Replace("+", "-")
                .Substring(0, 22);
        }

        public static Guid FromShortGuidString(this string value)
        {
            return new Guid(Convert.FromBase64String(value.Replace("_", "/")
                                                         .Replace("-", "+") + "=="));
        }

        public static string ToStringMaximumLength(this string value, int maximumLength)
        {
            return ToStringMaximumLength(value, maximumLength, "...");
        }

        public static string ToStringMaximumLength(this string value, int maximumLength, string postFixText)
        {
            if (string.IsNullOrEmpty(postFixText))
            {
                throw new ArgumentNullException("postFixText");
            }

            return value.Length > maximumLength
                       ? string.Format(CultureInfo.InvariantCulture,
                                       "{0}{1}",
                                       value.Substring(0, maximumLength - postFixText.Length),
                                       postFixText)
                       :
                           value;
        }

        public static string SlugDecode(this string value)
        {
            return value.Replace("_", " ");
        }

        public static string SlugEncode(this string value)
        {
            return value.Replace(" ", "_");
        }
    }
}

将字符串的长度减少到toLength，并在缩短的字符串的末尾添加一个额外的字符串，以表示字符串被缩短(默认值…)

public static string Shorten(this string str, int toLength, string cutOffReplacement = " ...")
{
    if (string.IsNullOrEmpty(str) || str.Length <= toLength)
        return str;
    else
        return str.Remove(toLength) + cutOffReplacement;
}

我经常用这个…

原始代码:

if (guid != Guid.Empty) return guid;
else return Guid.NewGuid();

新代码:

return guid.NewGuidIfEmpty();

扩展方法:

public static Guid NewGuidIfEmpty(this Guid uuid)
{
    return (uuid != Guid.Empty ? uuid : Guid.NewGuid());
}