C++_面向对象的引入

C++_面向对象的引入

前言：C语言过度到C++
下面从打印人的姓名和年龄为切入点

1、初学C语言时候的写法
注意：当需要打印很多人的信息的时候，需要列举非常多

#include 

int main(int argc, char **argv)
{
	char *zs_name = "zhangsan";
	int zs_age = 10;

	char *ls_name = "lisi";
	int ls_age = 16;

	printf("name = %s, age = %d\n", zs_name, zs_age);
	printf("name = %s, age = %d\n", ls_name, ls_age);
	
	return 0;
}
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2、使用数组存储多个人的信息
注意：属性越多增加的数组就越多，比如加入工作

#include 

int main(int argc, char **argv)
{
	char *names[] = {"zhangsan", "lisi"};
	char ages[] = {10, 16};
	char *work[] = {"teacher", "doctor"};
	
	int i;

	for (i = 0; i < 2; i++)
	{
		printf("name = %s, age = %d\n", names[i], ages[i]);	
	}
	
	return 0;
}
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3、引入C语言的结构体
注意：对于打印每个人的信息，引用的时候还是比较别扭的（persons[0].printInfo(&persons[0]);）有点让人不太好理解，后面向C++过度

#include 

struct person {
	char *name;
	int age;
	char *work;

	void (*printInfo)(struct person *per);
};

void printInfo(struct person *per)
{
	printf("name = %s, age = %d, work = %s\n", per->name, per->age, per->work);	
}
int main(int argc, char **argv)
{
	struct person persons[] = {
		{"zhangsan", 10, "teacher", printInfo},
		{"lisi", 16, "doctor", printInfo},
	};
	
	persons[0].printInfo(&persons[0]);
	persons[1].printInfo(&persons[1]);
	
	return 0;
}
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4、C++是在C的基础上变形而来的（对结构体扩展），类的核心就是结构体
注意这里是person5.cpp文件，这样编译或许有很多警告，但是可以编译通过的

#include 

struct person {
	char *name;
	int age;
	char *work;

	void printInfo(void)
	{
		printf("name = %s, age = %d, work = %s\n", name, age, work); 
	}
};

int main(int argc, char **argv)
{
	struct person persons[] = {
		{"zhangsan", 10, "teacher"},
		{"lisi", 16, "doctor"},
	};
	
	persons[0].printInfo();
	persons[1].printInfo();
	
	return 0;
}
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5、正式转到C++
注意：把struct换成class，并给内部参数添加属性（public）

#include 

class person {
public:
	char *name;
	int age;
	char *work;

	void printInfo(void)
	{
		printf("name = %s, age = %d, work = %s\n", name, age, work); 
	}
};

int main(int argc, char **argv)
{
	struct person persons[] = {
		{"zhangsan", 10, "teacher"},
		{"lisi", 16, "doctor"},
	};
	
	persons[0].printInfo();
	persons[1].printInfo();
	
	return 0;
}
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