Variables are simply names used to refer to some location in memory – a location that holds a value with which we are working. Size of variables depends upon data type used to define it.
Rules for defining variables in C
- The name of a variable can be composed of letters(a-z, A-Z), digits(0-9), and the underscore character(_).
- It must begin with either a letter or an underscore.
- Name is case-sensitive means Upper and lowercase letters are distinct.
- Blank spaces can't be used in variable names.
int EmployeeId; double Salary;
Incorrect Variable names
int 9people; //variable name can't start from number int zben?op; //? character not allowed
Lvalues and Rvalues in C
There are two kinds of expressions in C -
- lvalue - Expressions that refer to a memory location are called "lvalue" expressions. An lvalue may appear as either the left-hand or right-hand side of an assignment.
- rvalue - The term rvalue refers to a data value that is stored at some address in memory. It which means an rvalue must appear on the right-hand side but not on the left-hand side of an assignment.
int employeeId = 20; //valid statement 10 = 20; // invalid statement, compile-time error