C++第三篇--程序结构

1. 初识程序结构

将类中的成员函数全部放在类外实现，类中只负责声明该函数

person.cpp

#include <stdio.h>

class Person{

private:

    char *name;

    int  age;

    char *work;

public:

    void setName(char *name);

    int setAge(int age);

    void setWork(char *work);

    void printInfo(void);

};

void Person::setName(char *name)

{

    this->name = name;

}

int Person::setAge(int age)

{

        if(age<0 || age>200){

            this->age = 0;

            //return -1;

        }

        else

        {

            this->age = age;

        }

        return age;

}

void Person::setWork(char *work)

{

        this->work = work;

}

void Person::printInfo(void)

{

        printf("name is %s,age is %d,work is %s\n",name,age,work);

}

int main(int argc,char **arcv)

{

    Person per;

    per.setName("LKQ");

    per.setAge(20);

    per.setWork("Student");

    per.printInfo();

    return 0;

}

2. 改进上文程序结构

主要分为两个层次，一个类，一个主函数

• 实现Person类

  • Person.h:提供函数接口
  • Person.c:实现函数

• 实现主函数

person.h

#include <stdio.h>

class Person{

private:

    char *name;

    char age;

    char *work;

public:

    void setName(char *name);

    int setAge(int age);

    void setWork(char *work);

    void printInfo(void);

};

person.cpp

#include <stdio.h>

#include "person.h"

void Person::setName(char *name)

{

        this->name = name;

}

int Person::setAge(int age)

{

        if(age<0 || age>200){

            this->age = 0;

            //return -1;

        }

        else

        {

            this->age = age;

        }

        return age;

}

void Person::setWork(char *work)

{

        this->work = work;

}

void Person::printInfo(void)

{

        printf("name is %s,age is %d,work is %s\n",name,age,work);

}

main.cpp

#include <stdio.h>

#include "person.h"

int main(int argc,char **arcv)

{

    Person per;

    per.setName("LKQ");

    per.setAge(20);

    per.setWork("student");

    per.printInfo();

    return 0;

}

Makefile

person: main.o person.o

    g++ -o $@ $^

%.o : %.cpp

    g++ -c -o $@ $<

clean:

    rm -f *.o person

3. 添加一个Dog类

3.1 引入命名空间：为了解决多个人参加一个工程时，函数命名相同，调用同名函数时候声明属于哪个命名空间就可以解决。

dog.h

namespace c{

    class Dog{

    private:

        char *name;

        int age;

        char *work;

    public:

        void setName(char *name);

        int setAge(int age);

        void printInfo();

    };

    void PersonVersion(void);

}

dog.cpp

#include <stdio.h>

#include "dog.h"

namespace c{

    void Dog::setName(char *name)

    {

        this->name = name;

    }

    int Dog::setAge(int age)

    {

        if(age<0 || age>20)

        {

            this->age = 0;

            //return -1;

        }

        else

        {

            this->age = age;

        }

        return age;

    }

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

    void PersonVersion(void)

    {

        printf("Dog V1 by linkaiqiang");

    }

}

person.h

#include <stdio.h>

namespace A{

    class Person{

    private:

        char *name;

        char age;

        char *work;

    public:

        void setName(char *name);

        int setAge(int age);

        void setWork(char *work);

        void printInfo(void);

    };

    void PersonVersion(void);

}

person.cpp

#include <stdio.h>

#include "person.h"

namespace A{

    void Person::setName(char *name)

    {

        this->name = name;

    }

    int Person::setAge(int age)

    {

        if(age<0 || age>200){

            this->age = 0;

            //return -1;

        }

        else

        {

            this->age = age;

        }

        return age;

    }

    void Person::setWork(char *work)

    {

        this->work = work;

    }

    void Person::printInfo(void)

    {

        printf("name is %s,age is %d,work is %s\n",name,age,work);

    }

    void PersonVersion(void){

        printf("Person V1 by linkaiqiang");

    }

}

main.cpp

#include <stdio.h>

#include "person.h"

#include "dog.h"

int main(int argc,char **argv)

{

    A::Person per;

    per.setName("zhangsan");

    per.setAge(20);

    per.setWork("Student");

    per.printInfo();

    c::Dog dog;

    dog.setName("xiaozhao");

    dog.setAge(1);

    dog.printInfo();

    A::PersonVersion();

    printf("\n");

    c::PersonVersion();

    printf("\n");

    return 0;

}

Makefile

person: main.o person.o dog.o

    g++ -o $@ $^

%.o : %.cpp

    g++ -c -o $@ $<

clean:

    rm -f *.o person

3.2 直接使用类

修改main.cpp

#include <stdio.h>

#include "person.h"

#include "dog.h"

//global namespace

/*将A::person放入全局变量，以后可以用Person来表示A::person，下面同理*/

using A::Person;

using c::Dog;

/*

using A::PersonVersion;

using c::PersonVersion;

*/

//会发生冲突，如果是两个命名空间当中相同函数定义为全局

int main(int argc,int **arcv)

{

    //local namespace

    Person per;

    per.setName("zhangsan");

    per.setAge(20);

    per.setWork("Student");

    per.printInfo();

    Dog dog;

    dog.setName("xiaozhao");

    dog.setAge(1);

    dog.printInfo();

    A::PersonVersion();

    printf("\n");

    c::PersonVersion();

    printf("\n");

    return 0;

}

3.3使用namespace导入所有类和函数

修改main.cpp

#include <stdio.h>

#include "person.h"

#include "dog.h"

using namespace A;

using namespace c;

//将所有函数，所有类导入

int main(int argc,int **arcv)

{

    //local namespace

    Person per;

    per.setName("zhangsan");

    per.setAge(21);

    per.setWork("student");

    per.printInfo();

    Dog dog;

    dog.setName("xiaozhao");

    dog.setAge(1);

    dog.printInfo();

    A::PersonVersion();

    printf("\n");

    c::PersonVersion();

    printf("\n");

    return 0;

}

4. 引入iostream

之前的程序都是用printf实现打印函数，现在C++标准输出输入流实现

dog.h

namespace C {

class Dog{

private:

    char *name;

    int  age;

public:

    void setName(char *name);

    int setAge(int age);

    void printInfo();

};

void printVersion(void);

}

dog.cpp

#include <iostream>

#include "dog.h"

#include <stdio.h>

using namespace std;

namespace C {

    void Dog::setName(char *name)

    {

        this->name = name;

    }

    int Dog::setAge(int age)

    {

        if(age<0 || age>20){

            this->age = 0;

            return -1;

        }

        else

        {

            this->age = age;

        }

        return 0;

    }

    void Dog::printInfo()

    {

    cout<<"name is "<<name<<" age is "<<age<<endl;

    }

    void printVersion(void)

    {

        cout<<"Dog V1 by linkaiqiang"<<endl;;

    }

}

person.h

#include <stdio.h>

namespace A {

    class Person{

    private:

        char *name;

        int  age;

        char *work;

    public:

        void setName(char *name);

        int setAge(int age);

        void setWork(char *work);

        void printInfo(void);

    };

    void printVersion(void);

}

person.cpp

#include <iostream>

#include "person.h"

namespace A {

    void Person::setName(char *name)

    {

        this->name = name;

    }

    int Person::setAge(int age)

    {

        if (age < 0 || age > 150)

        {

            this->age = 0;

            return -1;

        }

        this->age = age;

        return 0;

    }

    void Person::setWork(char *work)

    {

        this->work = work;

    }

    void Person::printInfo(void)

    {

        std::cout<<"name = "<<name<<" age = "<<age<<" work = "<<work<<std::endl;

    }

    void printVersion(void)

    {

        std::cout<<"Person v1, by weidongshan"<<std::endl;

    }

}

main.cpp

#include "person.h"

#include "dog.h"

#include <stdio.h>

using namespace A;

using namespace C;

//将所有函数，所有类导入

int main(int argc,int **argv)

{

    //local namespace

    Person per;

    per.setName("zhangsan");

    per.setAge(20);

    per.setWork("student");

    per.printInfo();

    Dog dog;

    dog.setName("xiaozhao");

    dog.setAge(1);

    dog.printInfo();

    A::printVersion();

    printf("\n");

    C::printVersion();

    printf("\n");

    return 0;

}

Makefile

person: main.o person.o dog.o

g++ -o $@ $^

%.o : %.cpp

g++ -c -o $@ $<

clean:

rm -f *.o person

5. 总结

• 类定义(.h)/类实现(.cpp)
  • .h/.cpp文件中：

namespace a

//声明或定义函数;

int fun();

void fun2()...

• 命名空间
  • 直接使用: a::fun, a::fun2
  • using声明:using a::fun; // 以后调用fun即表示a::fun
  • using编译:using namespace a ; // 以后调用fun, fun2即可