A variable is a name of memory location. It is used to store data. Its value can be changed and it can be reused many times.
It is a way to represent memory location through symbol so that it can be easily identified.
The basic variable type available in C# can be categorized as:
Decimal, Boolean, Integral, Floating point, Nullable.
The example of declaring variable is given below:
int i, j; double d; float f; char ch;
Here, i, j, d, f, ch are variables and int, double, float, char are data types.
We can also provide values while declaring the variables as given below:
int i=2,j=4; //declaring 2 variable of integer type float f=40.2; char ch='B';
Rules for defining variables
1 – A variable can have alphabets, digits and underscore.
2 – A variable name can start with alphabet and underscore only. It can’t start with digit.
3 – No white space is allowed within variable name.
4 – A variable name must not be any reserved word or keyword e.g. char, float etc.
Valid variable names:
int x; int _x; int k20;
Invalid variable names:
int 4; int x y; int double;