c++ define中的三个特殊符号：#，##，#@

#include<iostream>
using namespace std;

#define Conn(x,y) x##y   //表示x连接y
#define tochar(x) #@x //给x加上单引号，结果返回是一个const char
#define tostring(x) #x  //给x加双引号 返回char const *

void test01()
{
	cout <<Conn(123,444) << endl; //123444
	cout <<Conn("abc", "efg") << endl; //abcefg


	auto a2 = tochar(4);
	cout << a2 << endl;  // a2='4'
	cout <<typeid(a2).name() << endl;


	auto a3 = tostring(43434);
	cout << a3 << endl; //a3="43434"
	cout << typeid(a3).name() << endl;
}


int main()
{	
	test01();
	system("pause");
	return 0;
}