C++ 引用

偷偷拿来记录一下萌新的cs路——day 20 继续学习C++基本知识 

#include
using namespace std;

//交换函数
//值传递
void swap01(int a, int b) {
	int temp = b;
	b = a;
	a = temp;
}
//地址传递
void swap02(int* a, int* b) {
	int temp = *b;
	*b = *a;
	*a = temp;
}
//引用传递
void swap03(int & a, int & b) {
	int temp = b;
	b = a;
	a = temp;
}

//引用作函数的返回值
int& test() {
	static int a = 10;  //静态变量存放全局区；不可使用局部变量，存放栈区
	return a;
}

//防止误操作
void showValue(const int &val) {
	//val = 100; //此举报错
	cout << "value = " << val << endl;
}

int main() {
	int a = 10;
	int& c = a;  // a别名b,引用须初始化
	cout << "a= " << a;
	cout << "tc= " << c << endl;

	int b = 20;
	//c = b;  //赋值，而非更改引用
	//cout << "a'= " << a << endl;
	//cout << "c'= " << c << endl;

	swap01(a, b);  //值传递，形参不会修饰实参
	cout << "swap01a= " << a;  
	cout << "tswap01b= " << b << endl;

	swap02(&a, &b);  //地址传递，形参修饰实参
	cout << "swap02a= " << a;
	cout << "tswap02b= " << b << endl;

	swap03(a, b);
	cout << "swap03a= " << a;
	cout << "tswap03b= " << b << endl;

	int& ref = test();
	cout << "ref = " << ref << endl;
	test() = 1000;  //a赋值1000,引用可作左值
	cout << "ref' = " << ref << endl;

	showValue(a);

	return 0;
}

运行结果