VB.NET Variable and Constant
In VB.NET, a variable is used to hold the value that can be used further in the programming. In this section, we will learn how to declare and initialize a variable and a constant.
What is a Variable?
A variable is a simple name used to store the value of a specific data type in computer memory. In VB.NET, each variable has a particular data type that determines the size, range, and fixed space in computer memory. With the help of variable, we can perform several operations and manipulate data values in any programming language.
VB.NET Variables Declaration
The declaration of a variable is simple that requires a variable name and data type followed by a Dim. A Dim is used in Class, Module, structure, Sub, procedure.
There are some valid declarations of variables along with their data type definition, as shown below:
Further, if we want to declare more than one variable in the same line, we must separate each variable with a comma.
Note: The statements given below is also used to declare the variable with their data type:
VB.NET Variable Initialization
After the declaration of a variable, we must assign a value to the variable. The following syntax describes the initialization of a variable:
We can also initialize a variable at the time of declaration:
Let's create a program to use different types of variable declaration and initialization in VB.NET.
Value of intData is: 10 Value of CharData is: A Value of strData is: VB.NET is a Programming Language. Value of dblData is: 4567.676 Value of single_data is: 23.08 press any key to exit...
Getting Values from the User in VB.NET
In VB.NET, the Console class provides the Readline() function in the System namespace. It is used to take input from the user and assign a value to a variable. For example:
Let's create a program that takes input from the user.
Enter your favourite number 7 Enter Your Good name Alexander Enter your Age 27.5 You have entered 7 You have entered Alexander You have entered 27.5
Note: Console.Read and Console.ReadKey() function is used to read a single character from the user.
Lvalues and Rvalues in VB.NET
There are two ways to express the expression value:
Lvalue: It is an lvalue expression that refers to a memory location for storing the address of a variable. An lvalue is a variable that can appear to the left or right of the assignment operator to hold values. Furthermore, in comparison to or swapping the variables' values, we can also define the variable on both sides (left or right-side) of the assignment operator.
But when we write the following statement, it generates a compile-time error because it is not a valid statement.
Rvalue: It is an rvalue expression that is used to store a value in some address of memory. An rvalue can appear only on the right- hand side because it is a value of the variable that defines on the right-hand side.
As the name suggests, the name constant refers to a fixed value that cannot be changed during the execution of a program. It is also known as literals. These constants can be of any data type, such as Integer, Double, String, Decimal, Single, character, enum, etc.
Declaration of Constants
In VB.NET, const is a keyword that is used to declare a variable as constant. The Const statement can be used with module, structure, procedure, form, and class.
Further, if we want to declare more than one variable in the same line, we must separate each variable with a comma, as shown below. The Syntax for defining the multiple variables as constant is:
Note: The statements given below are also used to declare the variable with their data type:
Example of Const keyword
Constant integer is 20 You have entered JavaTpoint Your Topic is VB.NET Enter the Radius 7 Area of Circle is 154
Scope of Variable in VB.NET
The scope of a variable determines the accessible range of a defined variable at the time of declaration in any block, module, and class. You can access it if the variable is in a particular region or scope in the same block. And if the variable goes beyond the region, its scope expires.
The following are the methods to represent the scope of a variable in VB.NET.
Procedure (local) scope
A local variable is a type of variable defined within a procedure scope, block, or function. It is available with a code inside the procedure, and it can be declared using the Dim or static statement. These variables are not accessible from outside of the local method. However, the local variable can be easily accessed by the nested programming function in the same method.
Local variables exist until the procedure in which they are declared is executed. Once a procedure is executed, the values of its local variables will be lost, and the resources used by these variables will be released. And when the block is executed again, all the local variables are rearranged.
Let's create a program that displays the local scope of a variable within a function.
Scope of local variable within a function Value of Local value X is 50 Value of X is JavaTpoint press any key to exit...
All existing procedures can easily identify a variable that is declared inside a module sheet is called a module-level variable. The defined module variable is visible to all procedures within that module only, but it is not available for other module's procedures. The Dim or private statement at the top of the first procedure declaration can be declared the module-level variables. It means that these variables cannot be declared inside any procedure block. Further, these variables are useful to share information between the procedures in the same module. And one more thing about the module-level variable is that these variables can remains existence as long as the module is executed.
' It is the declaration section of the module
Let's create a program that display the module level variable in VB.NET.
Module scope of variable Value of Y is 20 Value of X is 10 Value of Y is 20 Name is JavaTpoint Local scope within a function of variable A 30 Press any key to exit...
Global (Public) Scope
As the name defines, a global variable is a variable that is used to access the variables globally in a program. It means these variables can be accessed by all the procedures or modules available in a program. To access the variables globally in a program, you need to use the friend or public keyword with a variable in a module or class at the top of the first procedure function. Global scope is also known as the Namespace scope.
Let's create a program that uses the global variable.
You have passed Hello, Programmer Enter the topic name VB.NET Topic Name :VB.NET How many years of experienced in VB.NET? 10 Your Experienced is 10
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