这是一个位图扩展，可以将位图转换为灰度;

public static Bitmap GrayScale(this Bitmap bitmap)
{
    Bitmap newBitmap = new Bitmap(bitmap.Width, bitmap.Height);
    Graphics g = Graphics.FromImage(newBitmap);

    //the grayscale ColorMatrix
    ColorMatrix colorMatrix = new ColorMatrix(new float[][] {
            new float[] {.3f, .3f, .3f, 0, 0},
            new float[] {.59f, .59f, .59f, 0, 0},
            new float[] {.11f, .11f, .11f, 0, 0},
            new float[] {0, 0, 0, 1, 0},
            new float[] {0, 0, 0, 0, 1}
    });

    ImageAttributes attributes = new ImageAttributes();
    attributes.SetColorMatrix(colorMatrix);
    g.DrawImage(bitmap, new Rectangle(0, 0, bitmap.Width, bitmap.Height), 0, 0, bitmap.Width, bitmap.Height, GraphicsUnit.Pixel, attributes);
    g.Dispose();
    return newBitmap;
}

示例用法:

Bitmap grayscaled = bitmap.GrayScale()

我创建了一个扩展方法来在下拉菜单中选择一个项目。

下面是代码

 public static class Utilities
{
    public enum DropDownListSelectionType
    {
        ByValue,
        ByText
    }

    public static void SelectItem(this  System.Web.UI.WebControls.DropDownList drp, string selectedValue, DropDownListSelectionType type)
    {
        drp.ClearSelection();
        System.Web.UI.WebControls.ListItem li;
        if (type == DropDownListSelectionType.ByValue)
            li = drp.Items.FindByValue(selectedValue.Trim());
        else
            li = drp.Items.FindByText(selectedValue.Trim());
        if (li != null)
            li.Selected = true;
    }}

此方法可以由以下代码行调用，以按文本进行选择

DropDownList1.SelectItem("ABCD", Utilities.DropDownListSelectionType.ByText);

或者按值选择

DropDownList1.SelectItem("11", Utilities.DropDownListSelectionType.ByValue);

上面的代码不选择任何东西，如果它不能找到传递进来的文本/值。

如果你需要检查字符串的Is All char为0:

 static public bool   IsAllZero            (this string input)
        {
            if(string.IsNullOrEmpty(input))
                return true;
            foreach (char ch in input)
            {
                if(ch != '0')
                    return false;
            }
            return true;
        }

public static class StringHelper
{
    public static String F(this String str, params object[] args)
    {
        return String.Format(str, args);
    }
}

使用:

"Say {0}".F("Hello");

而与MVC工作，有很多if语句，我只关心或真或假，打印null，或字符串。在另一种情况下，我想到了:

public static TResult WhenTrue<TResult>(this Boolean value, Func<TResult> expression)
{
    return value ? expression() : default(TResult);
}

public static TResult WhenTrue<TResult>(this Boolean value, TResult content)
{
    return value ? content : default(TResult);
}

public static TResult WhenFalse<TResult>(this Boolean value, Func<TResult> expression)
{
    return !value ? expression() : default(TResult);
}

public static TResult WhenFalse<TResult>(this Boolean value, TResult content)
{
    return !value ? content : default(TResult);
}

它允许我改变<%= (someBool) ?print y:字符串。将%>空为<%= someBool。WhenTrue("print y") %>。

我只在我的视图中使用它，在这里我混合了代码和HTML，在代码文件中编写“更长的”版本更清楚。

public static bool In<T>(this T source, params T[] list)
{
  if(null==source) throw new ArgumentNullException("source");
  return list.Contains(source);
}

允许我替换:

if(reallyLongIntegerVariableName == 1 || 
    reallyLongIntegerVariableName == 6 || 
    reallyLongIntegerVariableName == 9 || 
    reallyLongIntegerVariableName == 11)
{
  // do something....
}

and

if(reallyLongStringVariableName == "string1" || 
    reallyLongStringVariableName == "string2" || 
    reallyLongStringVariableName == "string3")
{
  // do something....
}

and

if(reallyLongMethodParameterName == SomeEnum.Value1 || 
    reallyLongMethodParameterName == SomeEnum.Value2 || 
    reallyLongMethodParameterName == SomeEnum.Value3 || 
    reallyLongMethodParameterName == SomeEnum.Value4)
{
  // do something....
}

:

if(reallyLongIntegerVariableName.In(1,6,9,11))
{
      // do something....
}

and

if(reallyLongStringVariableName.In("string1","string2","string3"))
{
      // do something....
}

and

if(reallyLongMethodParameterName.In(SomeEnum.Value1, SomeEnum.Value2, SomeEnum.Value3, SomeEnum.Value4)
{
  // do something....
}