ASP.NET Razor - VB Variables

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ASP.NET Razor - VB Variables
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Variables are named entities used to store data.

Variables
Variables are used to store data.

The name of a variable must begin with an alphabetic character and cannot contain whitespace or reserved characters.

A variable can be of a specific type, indicating the kind of data it stores. String variables store string values ("Welcome to Omegas"), integer variables store number values (103), date variables store date values, etc.

Variables are declared using the Dim keyword, or by using the type (if you want to declare the type), but ASP.NET can usually determine data types automatically.

Examples
// Using the Dim keyword:
Dim greeting = "Welcome to Omegas"
Dim counter = 103
Dim today = DateTime.Today

// Using data types:
Dim greeting As String = "Welcome to Omegas"
Dim counter As Integer = 103
Dim today As DateTime = DateTime.Today
Data Types
Below is a list of  common data types:

Type Description Examples
integer Integer (whole numbers) 103, 12, 5168
double 64 bit floating-point number 3.14, 3.4e38
decimal Decimal number (higher precision) 1037.196543
boolean Boolean true, false
string String "Hello Omegas", "John"
Operators
An operator tells ASP.NET what kind of command to perform in an expression.

The VB language supports many operators. Below is a list of common operators:

Operator Description Example
= Assigns a value to a variable. i=6
+
-
*
/
Adds a value or variable.
Subtracts a value or variable.
Multiplies a value or variable.
Divides a value or variable. i=5+5
i=5-5
i=5*5
i=5/5
+=
-= Increments a variable.
Decrements a variable. i += 1
i -= 1
= Equality. Returns true if values are equal. if i=10
<> Inequality. Returns true if values are not equal. if <>10
<
>
<=
>= Less than.
Greater than.
Less than or equal.
Greater than or equal. if i<10
if i>10
if i<=10
if i>=10
& Adding strings (concatenation). "w3" & "schools"
. Dot. Separate objects and methods. DateTime.Hour
() Parenthesis. Groups values. (i+5)
() Parenthesis. Passes parameters. x=Add(i,5)
() Parenthesis. Accesses values in arrays or collections. name(3)
Not Not. Reverses true or false. if Not ready
And
OR Logical AND.
Logical OR. if ready And clear
if ready Or clear
AndAlso
orElse Extended Logical AND.
Extended Logical OR. if ready AndAlso clear
if ready OrElse clear
Converting Data Types
Converting from one data type to another is sometimes useful.

The most common example is to convert string input to another type, such as an integer or a date.

As a rule, user input comes as strings, even if the user entered a number. Therefore, numeric input values must be converted to numbers before they can be used in calculations.

Below is a list of common conversion methods:

Method Decryptions Example
AsInt()
IsInt() Converts a string to an integer. if myString.IsInt() then
   myInt=myString.AsInt()
end if
AsFloat()
IsFloat() Converts a string to a floating-point number. if myString.IsFloat() then
   myFloat=myString.AsFloat()
end if
AsDecimal()
IsDecimal() Converts a string to a decimal number. if myString.IsDecimal() then
   myDec=myString.AsDecimal()
end if
AsDateTime()
IsDateTime() Converts a string to an ASP.NET DateTime type. myString="10/10/2012"
myDate=myString.AsDateTime()
AsBool()
IsBool() Converts a string to a Boolean. myString="True"
myBool=myString.AsBool()
ToString() Converts any data type to a string. myInt=1234
myString=myInt.ToString()

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