简单但比“可枚举”更好。范围”,恕我直言:

/// <summary>
/// Replace "Enumerable.Range(n)" with "n.Range()":
/// </summary>
/// <param name="n">iterations</param>
/// <returns>0..n-1</returns>
public static IEnumerable<int> Range(this int n)
{
    for (int i = 0; i < n; i++)
        yield return i;
}

在单元测试中很有用:

public static IList<T> Clone<T>(this IList<T> list) where T : ICloneable
{
    var ret = new List<T>(list.Count);
    foreach (var item in list)
        ret.Add((T)item.Clone());

    // done
    return ret;
}

像TWith2Sugars这样的一系列，交替缩短语法:

public static long? ToNullableInt64(this string val)
{
    long ret;
    return Int64.TryParse(val, out ret) ? ret : new long?();
}

最后，在BCL中是否已经有一些东西做了下面的事情?

public static void Split<T>(this T[] array, 
    Func<T,bool> determinator, 
    IList<T> onTrue, 
    IList<T> onFalse)
{
    if (onTrue == null)
        onTrue = new List<T>();
    else
        onTrue.Clear();

    if (onFalse == null)
        onFalse = new List<T>();
    else
        onFalse.Clear();

    if (determinator == null)
        return;

    foreach (var item in array)
    {
        if (determinator(item))
            onTrue.Add(item);
        else
            onFalse.Add(item);
    }
}

我的建议:

public static bool IsNullOrEmpty(this ICollection obj)
{
  return (obj == null || obj.Count == 0);
}

使用集合和数组:

bool isNullOrEmpty = array.IsNullOrEmpty()

而不是

bool isNullOrEmpty = array == null || array.Length == 0;

我不想添加任何已经说过的东西，所以这里有一些我没有提到的东西。(如果这太长了，对不起):

public static class MyExtensions
{
    public static bool IsInteger(this string input)
    {
        int temp;

        return int.TryParse(input, out temp);
    }

    public static bool IsDecimal(this string input)
    {
        decimal temp;

        return decimal.TryParse(input, out temp);
    }

    public static int ToInteger(this string input, int defaultValue)
    {
        int temp;

        return (int.TryParse(input, out temp)) ? temp : defaultValue;
    }

    public static decimal ToDecimal(this string input, decimal defaultValue)
    {
        decimal temp;

        return (decimal.TryParse(input, out temp)) ? temp : defaultValue;
    }

    public static DateTime ToFirstOfTheMonth(this DateTime input)
    {
        return input.Date.AddDays(-1 * input.Day + 1);
    }

    // Intentionally returns 0 if the target date is before the input date.
    public static int MonthsUntil(this DateTime input, DateTime targetDate)
    {
        input = input.ToFirstOfTheMonth();

        targetDate = targetDate.ToFirstOfTheMonth();

        int result = 0;

        while (input < targetDate)
        {
        input = input.AddMonths(1);
            result++;
        }

        return result;
    }

    // Used for backwards compatibility in a system built before my time.
    public static DataTable ToDataTable(this IEnumerable input)
    {
        // too much code to show here right now...
    }
}

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!");

字符串。格式的快捷方式:

public static class StringExtensions
{
    // Enable quick and more natural string.Format calls
    public static string F(this string s, params object[] args)
    {
        return string.Format(s, args);
    }
}

例子:

var s = "The co-ordinate is ({0}, {1})".F(point.X, point.Y);

要快速复制粘贴，请点击这里。

难道你不觉得输入“一些字符串”. f(“param”)而不是字符串更自然吗?格式(“一些字符串”，“参数”)?

想要一个更容易读懂的名字，试试下面的建议:

s = "Hello {0} world {1}!".Fmt("Stack", "Overflow");
s = "Hello {0} world {1}!".FormatBy("Stack", "Overflow");
s = "Hello {0} world {1}!".FormatWith("Stack", "Overflow");
s = "Hello {0} world {1}!".Display("Stack", "Overflow");
s = "Hello {0} world {1}!".With("Stack", "Overflow");

..