Using static strings and objects to increase performance and maintainence

I found this global variable article below to help me with using static strings and objects to increase performance and maintainence.

For example, suppose I have an error message, "Error: ", that I might want to change to "There was a problem: ". Instead of search and replace n times, I could just use a static string variable to change the string value.

Sample Global class:

/// <summary>
/// Summary description for Global
/// </summary>
public static class Global
{
    public static string CSS_HIDDEN
    {
        get { return "hidden"; }
    }
    public static string CSS_EMPTY
    {
        get { return string.Empty; }
    }
    public static string CSS_CONTENT
    {
        get { return "content1"; }
    }
    public static string ERROR_HEADER_HTML
    {
        get { return "<red>There was a problem:</red></br>"; }
    }
    public static string ERROR_HEADER
    {
        get { return "There was a problem:"; }
    }
}

Then one just accesses it with Global.ERROR_HEADER. Notice that there is no declarative instantiation for the static class.

Reference: http://dotnetperls.com/Content/Global-Variables-ASPNET.aspx

C# switch statement for DropDownList to update Image url.

Simple control-flow statement to reference C# switch statement, which is similar to other language's case statement.

switch (DropDownList1.SelectedValue)
        {
            case "Image 1":
                imgFoo.ImageUrl = "images/photo1.jpg";
                break;
            case "Image 2":
                imgFoo.ImageUrl = "images/photo2.jpg";
                break;
            case "Image 3":
                imgFoo.ImageUrl = "images/photo3.jpg";
                break;
            default:
                imgFoo.ImageUrl = "images/photo_blank.jpg";
                break;
        }