The following are the types of expressions in C# −
lvalue − An expression that is an lvalue may appear as either the left-hand or right-hand side of an assignment.
rvalue − An expression that is an rvalue may appear on the right- but not left-hand side of an assignment.
Variables are lvalues and hence they may appear on the left-hand side of an assignment. Numeric literals are rvalues and hence they may not be assigned and cannot appear on the left-hand side.
Here is a valid C# statement −
int a = 100: