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

 1 #include <stdio.h>
 2 #include "person.h"
 3 #include "dog.h"
 4 
 5 /*global namespace*/
 6 /*把A::person放入global namespace，以后可以使用person来表示A::person*/
 7 using namespace A;
 8 using namespace C;
 9 
10 
11 int main(int argc,char ** argv)
12 {
13     /*local namespace*/
14     Person per;
15     Dog dog;
16     per.setName("zhangsan");
17     per.setAge(10);
18     per.printInfo();
19 
20     dog.setName("lisi");
21     dog.setAge(20);
22     dog.printInfo();
23     
24     A::printVersion();
25     C::printVersion();
26     return 0;
27 }

main.cpp

 1 #include <stdio.h>
 2 namespace A{
 3 
 4 class Person{
 5 private:
 6     char *name;
 7     int age;
 8     char *work;
 9 
10 public:
11     void setName(char *name);
12     int setAge(int Age);
13     void printInfo(void);
14 };
15 
16 void printVersion(void);
17 }

person.h

 1 #include <iostream>
 2 #include "person.h"
 3 using namespace std;
 4 
 5 namespace A{
 6 void Person::setName(char *name)
 7 {
 8     this->name = name;
 9 }
10 int Person::setAge(int Age)
11 {
12     if(Age < 0 || Age > 150)
13     {
14         this->age = 0;
15         return -1;
16     }
17     this->age = Age;
18     return 0;
19 }
20 void Person::printInfo(void)
21 {
22     cout<<"nane = "<<name<<"age = "<<age<<"work = "<<work<<endl;
23     //intf("name = %s, age = %d, work = %s
",name,age,work);
24 }
25 
26 void printVersion(void)
27 {
28     cout<<"Person V1, by luxiaoguo"<<endl;
29     //intf("Person V1, by luxiaoguo
");
30 }
31 
32 
33 }

person.cpp

 1 namespace C{
 2 
 3 class Dog{
 4 private:
 5     char *name;
 6     int age;
 7     char *work;
 8 
 9 public:
10     void setName(char *name);
11     int setAge(int age);
12     void printInfo(void);
13 };
14 
15 void printVersion(void);
16 
17 }

dog.h

 1 #include <stdio.h>
 2 #include "dog.h"
 3 
 4 namespace C{
 5 
 6 void Dog::setName(char *name)
 7 {
 8     this->name = name;
 9 }
10 int Dog::setAge(int Age)
11 {
12     if(Age < 0 || Age > 150)
13     {
14         this->age = 0;
15         return -1;
16     }
17     this->age = Age;
18     return 0;
19 }
20 void Dog::printInfo(void)
21 {
22     printf("name = %s, age = %d, work = %s
",name,age,work);
23 }
24 
25 void printVersion(void)
26 {
27     printf("Dog V1, by luxiaoguo
");
28 }
29 }

dog.cpp