An
expression is evaluated, and the result is saved in a variable:
wy = (m * x) + c;
w
w
int x, y;
x = 5;
y = 9;
cout << "The
value of x is " << x << endl;
cout << "The
value of y is " << y << endl;
int sum;
sum = x + y;
cout << "The sum
of x and y is " << sum << endl;
The assignment
will save the value of the expression in variable y.
Probably the
most common assignment operator is the equals sign (=).
It is called "assignment" because you are "assigning" a
variable to a value. This operator takes the expression on its
right-hand-side and places it into the variable on its left-hand-side. So,
when you write x = 5, the operator takes the expression on the
right, 5, and stores it in the variable on the left, x.
This code shows
why you might want to throw away the return value of an operator. Look at the
third line, x = 5. We're using the assignment operator here to
place the value 5 in the variable x.
Since the expression x = 5 returns a value, and we're not using
it, then you could say we are ignoring the return value. However, note that a
few of lines down, we are very interested in the return value of an operator.
The addition operator in the expression x + y returns the
sum of its left-hand-side and right-hand-side. That's how we are able to
assign a value to sum. You can think of it as sum = (x + y), since that's what it's really doing.