我创建了一个漂亮的Each扩展，具有与jQuery的Each函数相同的行为。

它允许如下所示，你可以获得当前值的索引，并通过返回false跳出循环:

new[] { "first", "second", "third" }.Each((value, index) =>
{
    if (value.Contains("d"))
        return false;
    Console.Write(value);
    return true;
});

下面是代码

/// <summary>
/// Generic iterator function that is useful to replace a foreach loop with at your discretion.  A provided action is performed on each element.
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="source"></param>
/// <param name="action">Function that takes in the current value in the sequence. 
/// <returns></returns>
public static IEnumerable<T> Each<T>(this IEnumerable<T> source, Action<T> action)
{
    return source.Each((value, index) =>
    {
        action(value);
        return true;
    });
}


/// <summary>
/// Generic iterator function that is useful to replace a foreach loop with at your discretion.  A provided action is performed on each element.
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="source"></param>
/// <param name="action">Function that takes in the current value and its index in the sequence.  
/// <returns></returns>
public static IEnumerable<T> Each<T>(this IEnumerable<T> source, Action<T, int> action)
{
    return source.Each((value, index) =>
    {
        action(value, index);
        return true;
    });
}

/// <summary>
/// Generic iterator function that is useful to replace a foreach loop with at your discretion.  A provided action is performed on each element.
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="source"></param>
/// <param name="action">Function that takes in the current value in the sequence.  Returns a value indicating whether the iteration should continue.  So return false if you don't want to iterate anymore.</param>
/// <returns></returns>
public static IEnumerable<T> Each<T>(this IEnumerable<T> source, Func<T, bool> action)
{
    return source.Each((value, index) =>
    {
        return action(value);
    });
}

/// <summary>
/// Generic iterator function that is useful to replace a foreach loop with at your discretion.  A provided action is performed on each element.
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="source"></param>
/// <param name="action">Function that takes in the current value and its index in the sequence.  Returns a value indicating whether the iteration should continue.  So return false if you don't want to iterate anymore.</param>
/// <returns></returns>
public static IEnumerable<T> Each<T>(this IEnumerable<T> source, Func<T, int, bool> action)
{
    if (source == null)
        return source;

    int index = 0;
    foreach (var sourceItem in source)
    {
        if (!action(sourceItem, index))
            break;
        index++;
    }
    return source;
}

我经常用这个来表示可为空的数字。我帮助用0,NaN，无穷大…

public static bool IsNullOrDefault<T>(this T? o) 
    where T : struct
{
        return o == null || o.Value.Equals(default(T));
}

内联转换:我喜欢这个小模式。完成了Boolean, Double和DateTime。设计遵循c#的is和作为操作符。

public static Int32? AsInt32(this string s)
{
    Int32 value;
    if (Int32.TryParse(s, out value))
        return value;

    return null;
}

public static bool IsInt32(this string s)
{
    return s.AsInt32().HasValue;
}

public static Int32 ToInt32(this string s)
{
    return Int32.Parse(s);
{

在将表单输入放入数据库之前解析表单输入时，这些扩展方法对我来说非常有用

public static int? ToInt(this string input) 
{
    int val;
    if (int.TryParse(input, out val))
        return val;
    return null;
}

public static DateTime? ToDate(this string input)
{
    DateTime val;
    if (DateTime.TryParse(input, out val))
        return val;
    return null;
}

public static decimal? ToDecimal(this string input)
{
    decimal val;
    if (decimal.TryParse(input, out val))
        return val;
    return null;
}

将double类型转换为使用指定区域性格式化的字符串:

public static class ExtensionMethods 
{
  public static string ToCurrency(this double value, string cultureName)
  {
    CultureInfo currentCulture = new CultureInfo(cultureName);
    return (string.Format(currentCulture, "{0:C}", value));
  }
}

例子:

double test = 154.20;
string testString = test.ToCurrency("en-US"); // $154.20

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;
}