ariable declarations require a type, a name and, optionally a value assignment. The following example declares an integer variable called interestRate but does not initialize it:
The following example declares and initializes a variable using the assignment operator (=):
int interestRate = 10;
A new value may be assigned to a variable at any point after it has been declared.
int interestRate = 5; //Declare the variable and initialize it to 5 interestRate = 10; // variable now equals 10 interestRate = 20; // variable now equals 20
A constant is similar to a variable in that it provides a named location in memory to store a data value. Constants differ in one significant way in that once a value has been assigned to a constant it cannot subsequently be changed.
Constants are particularly useful if there is a value which is used repeatedly throughout the application code. Rather than use the value each time, it makes the code easier to read if the value is first assigned to a constant which is then referenced in the code. For example, it might not be clear to someone reading your C# code why you used the value 5 in an expression. If, instead of the value 5, you use a constant n