003_linuxC++之_namespace使用

（一）引入namespace原因：

假如有很多跟人共同完成一项工程，工程中难免会有函数定义一样的名称，不可能一个一个的询问这个函数 你定义过了没有，所以引入namespace

 #include <stdio.h>
 #include "person.h"
 #include "dog.h"

 /*global namespace*/
 /*把A::person放入global namespace，以后可以使用person来表示A::person*/
 using namespace A;
 using namespace C;

 int main(int argc,char ** argv)
 {
     /*local namespace*/
     Person per;
     Dog dog;
     per.setName("zhangsan");
     per.setAge();
     per.printInfo();

     dog.setName("lisi");
     dog.setAge();
     dog.printInfo();

     A::printVersion();
     C::printVersion();
     return ;
 }

main.cpp

 #include <stdio.h>
 namespace A{

 class Person{
 private:
     char *name;
     int age;
     char *work;

 public:
     void setName(char *name);
     int setAge(int Age);
     void printInfo(void);
 };

 void printVersion(void);
 }

person.h

 #include <iostream>
 #include "person.h"
 using namespace std;

 namespace A{
 void Person::setName(char *name)
 {
     this->name = name;
 }
 int Person::setAge(int Age)
 {
     if(Age <  || Age > )
     {
         this->age = ;
         return -;
     }
     this->age = Age;
     return ;
 }
 void Person::printInfo(void)
 {
     cout<<"nane = "<<name<<"age = "<<age<<"work = "<<work<<endl;
     //intf("name = %s, age = %d, work = %s\n",name,age,work);
 }

 void printVersion(void)
 {
     cout<<"Person V1, by luxiaoguo"<<endl;
     //intf("Person V1, by luxiaoguo\n");
 }

 }

person.cpp

 namespace C{

 class Dog{
 private:
     char *name;
     int age;
     char *work;

 public:
     void setName(char *name);
     int setAge(int age);
     void printInfo(void);
 };

 void printVersion(void);

 }

dog.h

 #include <stdio.h>
 #include "dog.h"

 namespace C{

 void Dog::setName(char *name)
 {
     this->name = name;
 }
 int Dog::setAge(int Age)
 {
     if(Age <  || Age > )
     {
         this->age = ;
         return -;
     }
     this->age = Age;
     return ;
 }
 void Dog::printInfo(void)
 {
     printf("name = %s, age = %d, work = %s\n",name,age,work);
 }

 void printVersion(void)
 {
     printf("Dog V1, by luxiaoguo\n");
 }
 }

dog.cpp