An expression is a sequence of operators and operands (variables or literals) that results in some value. Consider the following:
int i; i = 6 * 7;
On the right side 6 * 7 is an expression, and the assignment (from i on the left-hand side to the semicolon on the right) is a statement.
Every expression is either an lvalue or an rvalue. You are most likely to see these keywords used in error descriptions. In effect, an lvalue is an expression that refers to some memory location. Items on the left-hand side of an assignment must be lvalues. However, an lvalue can appear on the left- or right-hand side of an assignment. All variables are lvalues. An rvalue is a temporary item that does not exist longer than the expression ...
