Conditional Logic and Loops
ASP.NET server code lets you perform tasks based on conditions and write code that repeats statementsa specific number of times (loops).
Testing Conditions
To test a simple condition you use the if statement, which returns true or false based on a test youspecify:


 @{var showToday = true;if(showToday){@DateTime.Today;}}

        @{
            showToday = false;
            if(showToday)
            {
                @DateTime.Today;
            }
            else
            {
                <br />
                <text>Sorry!</text>
            }}



9/13/2012 12:00:00 AM
Sorry!
If else Code
You can add multiple conditions using an else if block:


@{
            var theBalance = 4.99;
           if(theBalance == 0)
           {
                      <p>You have a zero balance.</p>        
           }
            else if (theBalance > 0 && theBalance <= 5)
            {
            <p>Your balance of $@theBalance is very low.</p>
            }
            else
            {
            <p>Your balance is: $@theBalance</p>
            }
            }



Your balance of $4.99 is very low.
Switch case Code
To test a large number of conditions, use a switch block:


 @{
                var weekday = "Wednesday";
                var greeting = "";
                switch (weekday)
                {
                    case "Monday":
                        greeting = "Ok, it's a marvelous Monday";
                        break;
                    case "Tuesday":
                        greeting = "It's a tremendous Tuesday";
                        break;
                    case "Wednesday":
                        greeting = "Wild Wednesday is here!";
                        break;
                    default:
                        greeting = "It's some other day, oh well.";
                        break;
                }
                <p>Since it is @weekday, the message for today is: @greeting</p>
                }



Since it is Wednesday, the message for today is: Wild Wednesday is here!
For Looping Code
 @for(var i = 10; i < 21; i++){<p style="font-size: @(i + "pt")">My font size is now: @i</p>}

My font size is now: 10
My font size is now: 11
My font size is now: 12
My font size is now: 13
My font size is now: 14
My font size is now: 15
My font size is now: 16
My font size is now: 17
My font size is now: 18
My font size is now: 19
My font size is now: 20
For each Looping Code
<ul>@foreach (var myItem in Request.ServerVariables){<li>@myItem</li>}</ul>
ALL_HTTP
ALL_RAW
APPL_MD_PATH
APPL_PHYSICAL_PATH
AUTH_TYPE
AUTH_USER
AUTH_PASSWORD
LOGON_USER
REMOTE_USER
CERT_COOKIE
CERT_FLAGS
CERT_ISSUER
CERT_KEYSIZE
CERT_SECRETKEYSIZE
CERT_SERIALNUMBER
CERT_SERVER_ISSUER
CERT_SERVER_SUBJECT
CERT_SUBJECT
CONTENT_LENGTH
CONTENT_TYPE
GATEWAY_INTERFACE
HTTPS
HTTPS_KEYSIZE
HTTPS_SECRETKEYSIZE
HTTPS_SERVER_ISSUER
HTTPS_SERVER_SUBJECT
INSTANCE_ID
INSTANCE_META_PATH
LOCAL_ADDR
PATH_INFO
PATH_TRANSLATED
QUERY_STRING
REMOTE_ADDR
REMOTE_HOST
REMOTE_PORT
REQUEST_METHOD
SCRIPT_NAME
SERVER_NAME
SERVER_PORT
SERVER_PORT_SECURE
SERVER_PROTOCOL
SERVER_SOFTWARE
URL
HTTP_CONNECTION
HTTP_ACCEPT
HTTP_ACCEPT_ENCODING
HTTP_ACCEPT_LANGUAGE
HTTP_COOKIE
HTTP_HOST
HTTP_REFERER
HTTP_USER_AGENT
HTTP_DNT
While Looping Code
@{var countNum = 0;while (countNum < 50){countNum += 1;<p>Line #@countNum: </p>}}

Line #1:
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