#include <iostream>
using namespace std;
class class1 {
public:
class1(){
}
class1(int i ){
}
void show(){
cout<<"this is output by class1 ! \n ";
}
};
int main(){
// static allocation :
/*
class1 oneclass();
oneclass.show();
error : request show() function of non-class oneclass .
because : compile thinks of oneclass1 oneclass() as of function declaration with
name 'oneclass' and the return type class1
*/
/*
class1 secondclass(1);
secondclass.show();
*/
//dynamic allocation :
class1 * thirdclass = new class1();
thirdclass->show();
return 0;
}

总结一下:
1. 当使用类的无参构造函数来实例化对象时,有两种方法:
类名 * x = new 类名();
类名 x;
2 . 当使用有参的构造函数时,有两种方法:
类名 * x = new 类名(参数列表);
类名 x(参数列表);
注 :编译器版本 :