[C++知识库]C++普通类型与类类型的互转

1.普通类型转类类型

需求：

??????? Human boy1 =10000;? //薪资? 可以用构造函数Human(int)构造函数实现

??????? Human boy2 = 张三";? //姓名? 可以用构造函数Human(char *)构造函数实现

#include<string>
#include<iostream>

class boy {
public:
	boy(int salare);
	boy(const char* name);
	~boy();
	void description();
private:
	int salare;
	char* name;
};

//boy(int)构造函数
boy::boy(int salare) {
	const char* name = "name为空";
	this->name = new char[strlen(name) + 1];
	strcpy_s(this -> name, strlen(name) + 1, name);
	this->salare = salare;
}

//boy(const char *)构造函数
boy::boy(const char* name) {
	this->salare = 0;
	this->name = new char[strlen(name) + 1];
	strcpy_s(this->name, strlen(name) + 1, name);
}

boy::~boy() {
	delete[] this->name;
}

void boy::description() {
	std::cout << "姓名：" << this->name << std::endl;
	std::cout << "薪资：" << this->salare << std::endl;
}

int main() {
	boy boy1 = 10000;
	boy boy2 = "Jack";
	boy1.description();
	boy2.description();
	system("pause");
	return 0;
}

?

?

2.类类型转普通类型

调用特殊的运算符重载函数，类型转换函数，不需要写返回类型

类型转换函数：operator 普通类型（）;

需求：

Boy boy1(“Jack”, 10000);

int ?salare= boy1; ??// salare;

char *name = boy1; ??// “Jack”

#include<string>
#include<iostream>

class boy {
public:
	boy(const char* name, int salare);
	~boy();
	//转int 类型  也可以不加const
	//类型运算符重载，不需要返回类型
	operator int() const;

	operator char* ()const;

private:
	int salare;
	char* name;
};

//直接返回类型
boy::operator int()const {
	return this->salare;
}
//直接返回类型
boy::operator char* ()const {
	return this->name;
}

boy::boy(const char* name, int salare) {
	if (!name) {
		name = "name为空";
	}
	this->name = new char[strlen(name) + 1];
	strcpy_s(this->name, strlen(name) + 1, name);
	this->salare = salare;
}


boy::~boy() {
	delete[] this->name;
}


int main() {
	boy boy1("Jack", 10000);
	int salare = boy1;
	char* name = boy1;
	std::cout << "姓名：" << name << "薪资：" << salare << std::endl;
	system("pause");
	return 0;
}

?

?

3.类类型转类类型

调用对应的构造函数，参数类型就是类A

实例：

把Boy类型，转换为Man类型

#include<string>
#include<iostream>

class boy {
public:
	boy(const char* name, int salare);
    operator char* ()const;
	~boy();
private:
	int salare;
public:
	char* name;
};

boy::boy(const char* name, int salare) {
	if (!name) {
		name = "name为空";
	}
	this->name = new char[strlen(name) + 1];
	strcpy_s(this->name, strlen(name) + 1, name);
	this->salare = salare;
}

boy::operator char* ()const {
	return this->name;
}

boy::~boy() {
	delete[] this->name;
}

class Man {
public:
	Man(const boy* boy);
	~Man();
	char* name;
};

Man::Man(const boy* boy) {
	this->name = new char[strlen((char*)*boy + 1];
	strcpy_s(this->name, (char*)*boy + 1, boy->name);
}
Man::~Man() {
	delete[]this->name;
}

int main() {
	boy boy1("Jack", 10000);
	Man man1 = &boy1;
	std::cout << man1.name<<std::endl;
	system("pause");
	return 0;
}