[开发工具]C++的优先级：先-＞再++

1.若有以下说明语句和定义语句，则下面表达式中值为3的是

#include<iostream>
using namespace std;

int main() {
	
	struct s {
		int i1;
		struct s *i2;
	};

	static struct s a[3] = { 1,&a[1],2,&a[2],3,&a[0] };
	static struct s *ptr;
	ptr = &a[1];

	//选项A
	//cout << ptr->i1++ << endl;//2
	//选项B
	//cout << ptr++->i1 << endl;//2
	//选项C
	//cout << *ptr->i1 << endl;//报错，*的操作数必须是指针
	//选项D
	cout << ++ptr->i1 << endl;//3，先->再++
	return 0;
}

?2.输出值为6的是

int main() {

	struct st {
		int n;
		struct st *next;
	};
	static  st a[3] = { 5,&a[1],7,&a[2],9,NULL }, *p;
	p = &a[0];
	//选项A  先->再++ 
	//cout << p++->n << endl;//5
	//cout<<p->n<<endl;//7
	//选项B  先->再++ 
	//cout << p->n++ << endl;//5
	//cout<<p->n<<endl;//6
	//选项C 
	//cout << (*p).n++ << endl;//5
	//cout<<p->n<<endl;//6
	//选项D
	//cout << (++p)->n << endl;//7
	//cout << ++(p->n) << endl;//6，
	cout << ++p->n << endl;//6，->优先级高于++	
	return 0;
}

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