C# Basics-Vaiables in C# (C#-6)

Variables in C#

what is a variable?

• A variable is simply a named storage location in your program's memory that holds a value.

• This value can be changed during program execution, making variables a powerful tool for manipulating data.

Declaring a Variable

• To use a variable in your program, you must first declare it. This means you need to specify its data type and give it a name.

• The data type defines the kind of data that the variable can hold, such as numbers or text. we will talk more about data types in the next chapter.

• For example, you can declare a variable that holds an integer value as:(C-1-1)

(C-1-1)

• The above example creates a variable named myVariable that can hold integer values. 

Note:

The semicolon at the end of the line is required to indicate the end of the statement.

Initializing a Variable

• You can also initialize a variable when you declare it. This means you give it an initial value that it held when it was first created. 

• You can simply assign a value to the variable using the equal sign to do this.

• For example, to declare and initialize a variable named myVariable that holds the value 10, you would write:(C-1-2)

(C-1-2)

Using a Variable

• Once you have declared and initialized a variable, you can use it in your program. 

• You can use the variable's name to refer to its current value or change its value by assigning a new value to it.

• For example, you can use a variable to add two numbers and store the result in a third variable as:(C-1-3)

(C-1-3)

• In the above example, we create two variables named variable1 and variable2 that hold the values 10 and 15 respectively. Then we create a third variable named summation and assign it to the value of variable1 + variable2, which will be 25.

You can also display the summation on the console using WriteLine or write methods. (C-1-4)

(C-1-4)

Rules for declaring variables in programming

• Variable names must begin with a letter or an underscore (_).

• Variable names cannot begin with a number.

• Variable names can only contain letters, numbers, and underscores(No special characters such as @,#,$,%,& except underscores).

• Variable names are case-sensitive.

• Variable names should be descriptive and meaningful.

• Variables must be declared with a data type.

• The data type of a variable determines the type of values it can hold.

• Variables can be initialized at the time of declaration, or later in the code.

• Multiple variables of the same data type can be declared on the same line, separated by commas.Example(C-1-5)

(C-1-5)

Constants in C#

• A constant variable is a variable whose value cannot be changed once it has been assigned a value.

• It is declared using the const keyword followed by the data type and the variable name.

Example of how to declare a constant variable in C#:(C-1-6)

(C-1-6)

• In the above example, we have declared a constant variable named myConstant of type int and assigned it a value of 10.

• Once the value of a constant variable is set, it cannot be changed during the execution of the program. 

• Attempting to change the value of a constant variable will result in a compile-time error.

Conclusion

Variables are a fundamental concept in programming, and learning how to use them is an 

essential part of becoming a proficient programmer. By understanding how to declare, initialize, and use variables, you can create powerful programs that manipulate data in useful ways.

Activity

Write a C# program that declares a variable named age and assigns it the value of your age. 

Then, declare another variable as a name and assign it the value to your name. Finally, print the values of both variables to the console.

post your answer in the comment section.

Catch you at that next one😍