总习惯用c的用法,现在学习C++,老爱拿来比较。声明我用的是g++4.2.1 SUSE Linux。看例子吧
- #include <iostream>
- #include <cstring>
- #include <string>
- using namespace std;
- enum zoo_obj_kind{
- null = 0,
- #define null null
- no = 0,
- #define no no
- animal = 2,
- #define animal animal
- plant = 4,
- #define plant plant
- others = 8
- #define others others
- };
- struct zoo_obj{
- zoo_obj_kind zo_kind;
- char name [40];
- };
- class zoo_obj_1{
- zoo_obj_kind zo_kind;
- char name [40];
- };
- int main(void){
- cout << "struct :" << sizeof(struct zoo_obj) << endl;
- cout << "clsas :" << sizeof( zoo_obj_1) << endl;
- }
结果
- struct size:44
- clsas size:44
-------------------------------
- #include <iostream>
- #include <cstring>
- #include <string>
- using namespace std;
- enum zoo_obj_kind{
- null = 0,
- #define null null
- no = 0,
- #define no no
- animal = 2,
- #define animal animal
- plant = 4,
- #define plant plant
- others = 8
- #define others others
- };
- struct zoo_obj{
- zoo_obj_kind zo_kind;
- char name [40];
- void (*say)(struct zoo_obj *);
- };
- void say(struct zoo_obj *obj){
- if(!obj) {
- printf("null\n");
- return ;
- }
- printf("name:%s\n",obj->name);
- }
- class zoo_obj_1{
- zoo_obj_kind zo_kind;
- char name [40];
- void say(zoo_obj_1 &obj){
- cout << "name:" << name << endl;
- }
- };
- int main(void){
- cout << "struct :" << sizeof(struct zoo_obj) << endl;
- cout << "clsas :" << sizeof( zoo_obj_1) << endl;
- }
结果
- struct size:48
- clsas size:44
呵呵,有意思吧,在class中成员函数不占空间。下面你看看他们有多像
- #include <iostream>
- #include <cstring>
- #include <string>
- using namespace std;
- enum zoo_obj_kind{
- null = 0,
- #define null null
- no = 0,
- #define no no
- animal = 2,
- #define animal animal
- plant = 4,
- #define plant plant
- others = 8
- #define others others
- };
- struct zoo_obj{
- zoo_obj_kind zo_kind;
- char name [40];
- void (*say)(struct zoo_obj &);
- };
- void say(struct zoo_obj &obj){
- printf("name:%s\n",obj.name);
- }
- class zoo_obj_1{
- public:
- zoo_obj_kind zo_kind;
- char name [40];
- void say(){cout << "name:" << name << endl;}
- void say(zoo_obj_1 &obj){cout << "name:" << obj.name << endl;}
- };
- typedef struct zoo_obj s_zoo_obj;
- typedef zoo_obj_1 c_zoo_obj;
- int main(void){
- s_zoo_obj s_obj = {animal,"dog",say};
- zoo_obj_1 c_obj = {animal,"cat"};
- cout << "struct size:" << sizeof(struct zoo_obj) << endl;
- cout << "clsas size:" << sizeof( zoo_obj_1) << endl;
- s_obj.say(s_obj);
- c_obj.say(c_obj);
- }
结果
- struct size:48
- clsas size:44
- name:dog
- name:cat
这是同时使用了引用,那么指针呢。struct的指针当然没有问题,那么class的指针呢?看看代码
- #include <iostream>
- #include <cstring>
- #include <string>
- using namespace std;
- enum zoo_obj_kind{
- null = 0,
- #define null null
- no = 0,
- #define no no
- animal = 2,
- #define animal animal
- plant = 4,
- #define plant plant
- others = 8
- #define others others
- };
- struct zoo_obj{
- zoo_obj_kind zo_kind;
- char name [40];
- void (*say)(struct zoo_obj *);
- };
- void say(struct zoo_obj *obj){
- !obj
- ? printf("null\n")
- : printf("name:%s\n",obj->name);
- }
- class zoo_obj_1{
- public:
- zoo_obj_kind zo_kind;
- char name [40];
- void say(){cout << "name:" << name << endl;}
- void say(zoo_obj_1 *obj){
- !obj
- ? cout << "null\n"
- : cout << "name:" << obj->name << endl;
- }
- };
- typedef struct zoo_obj s_zoo_obj;
- typedef zoo_obj_1 c_zoo_obj;
- int main(void){
- s_zoo_obj s_obj = {animal,"dog",say};
- zoo_obj_1 c_obj = {animal,"cat"};
- cout << "struct size:" << sizeof(struct zoo_obj) << endl;
- cout << "clsas size:" << sizeof( zoo_obj_1) << endl;
- s_obj.say(&s_obj);
- c_obj.say(&c_obj);
- s_obj.say(NULL);
- c_obj.say(NULL);
- }
哈哈,结果仍然是
- struct size:48
- clsas size:44
- name:dog
- name:cat
更高级的特性呢?
比如在继承,接口。。。
个人认为C的这类名词没有,但他确实能出色的实现诸如此类的功能,而且更直观。可能是我的C++还不行吧。C高效和简单直观是没得说的。
时间: 2024-10-06 06:58:40