技術標籤：C++の相關概念

字首++與字尾++的本指區別是什麼？

int i = 0, n = 0;

int test = ++i;
//此時，test等於1，i也等於1
test = n++;
//此時，test等於0，n等於1
因此，要說本質區別就是字首加加返回自增後的自己，而後綴加加是返回自增前的值

字首++與字尾++的類成員函式過載是怎樣的？

Complex& operator++()//字首++過載 返回的是引用
Complex operator++(int)// 字尾++過載寫法 (int) 區分字首的必須寫成int 返回是右值物件
字首++返回引用，字尾++返回右值！！！
所以沒有int i=1; i++++;

假設it為指標*(it++)和*(++it）和*it++和*++it和(*it)++和++(*it)的區別是什麼？

• *it++ 和 *(it++) 的結果是一樣的
  先執行*it返回結果，再將it++
• *++it 和 *(++it) 的結果是一樣的
  先執行it++，再將*it返回結果
  簡而言之，加不加括號沒有改變結果…
• (*it)++顧名思義就是先取*it的值，然後再把解地址處的值進行++
  (*it)++顧名思義就是先把解地址處的值進行++，然後再取*it的值

以下是測試程式碼以及結果：

void
 
 test(int* it, int situation) {
	if (situation == 1) {
		cout << "*it = " << *it << endl;
		int tmp = *(it++);
		cout << "tmp = *(it++) = " << tmp << endl;
		cout << "now *it = " << *it << endl;
	}
	else if (situation ==
 
 2) {
		cout << "*it = " << *it << endl;
		int tmp = *(++it);
		cout << "tmp = *(++it) = " << tmp << endl;
		cout << "now *it = " << *it << endl;
	}
	else if (situation == 3) {
		cout << "*it = " << *it << endl;
		int tmp = *it++;
		cout << "tmp = *it++ = " << tmp << endl;
		cout << "now *it = " << *it << endl;
	}
	else if (situation == 4) {
		cout << "*it = " << *it << endl;
		int tmp = *++it;
		cout << "tmp = *++it = " << tmp << endl;
		cout << "now *it = " << *it << endl;
	}
	else if (situation == 5) {
		cout << "*it = " << *it << endl;
		int tmp = (*it)++;
		cout << "tmp = (*it)++ =" << tmp << endl;
		cout << "now *it = " << *it << endl;
	}
	else if (situation == 6) {
		cout << "*it = " << *it << endl;
		int tmp = ++(*it);
		cout << "tmp = ++(*it) = " << tmp << endl;
		cout << "now *it = " << *it << endl;
	}
	else {
		cout << "error;" << endl;
	}
}

int main() {
	int a[10] = { 1,2,3,4,5,6,7,8,9 };
	test(a + 3, 1);
	cout << endl;
	test(a + 3, 2);
	cout << endl;
	test(a + 3, 3);
	cout << endl;
	test(a + 3, 4);
	cout << endl;
	test(a + 3, 5);
	cout << endl;
	test(a + 3, 6);
	cout << endl;
	return 0;
}