一元運算子

一元運算子作用於它們被呼叫的物件並具有高優先順序。 （見備註）

使用 postfix 時，只有在評估整個操作後才會執行操作，從而產生一些有趣的算術：

int a = 1;
++a;            // result: 2
a--;            // result: 1
int minusa=-a;  // result: -1

bool b = true;
!b; // result: true

a=4;
int c = a++/2;      // equal to: (a==4) 4 / 2   result: 2 ('a' incremented postfix)
cout << a << endl;  // prints 5!
int d = ++a/2;      // equal to: (a+1) == 6 / 2 result: 3

int arr[4] =  {1,2,3,4};

int *ptr1 = &arr[0];    // points to arr[0] which is 1
int *ptr2 = ptr1++;     // ptr2 points to arr[0] which is still 1; ptr1 incremented
std::cout << *ptr1++ << std::endl;  // prints  2

int e = arr[0]++;       // receives the value of arr[0] before it is incremented
std::cout << e << std::endl;      // prints 1
std::cout << *ptr2 << std::endl;  // prints arr[0] which is now 2