In addition to incrementing and decrementing a variable by one, it is common to increment/decrement by more than one.
int a = 1, b = 6; a = a + 5; // add 5 to a b = b - 4; // subtract 4 from b a = a + 1; // add 1 to a
C++ has several operators that aid in these kinds of operations. These operators have the same precedence as the assignment operator,
=. Assume:int x = 8;
|
Operator |
Example |
Equivalent long form |
Result |
|
+= |
x += 3 |
x = x + 3 |
11 |
|
-= |
x -= 4 |
x = x - 4 |
4 |
|
*= |
x *= 2 |
x = x * 2 |
16 |
|
/= |
x /= 2 |
x = x / 2 |
4 |
|
%= |
x %= 2 |
x = x % 2 |
0 |
The example above can be re-written as:
int a = 1, b = 6; a += 5 // a is now 6 b -= 4; // b is now 2 a += 1; // a is now 7 (same as a++)Previous slide