Friend

来源：互联网发布：数据灾备计划编辑：程序博客网时间：2024/06/11 13:03

friend class for each other

#include <iostream>#include <string.h>using namespace std;class Curly { public:   Curly(char *msg) { strcpy(message, msg); };   void show_message(void) { cout << message << endl; };   friend class Moe;   void show_moe(class Moe moe); private:   char message[256]; };class Moe { public:   Moe(char *msg) { strcpy(message, msg); };   void show_message(void) { cout << message << endl; };   friend class Curly;   void show_curly(class Curly curly); private:   char message[256]; };void Curly::show_moe(class Moe moe) { cout << moe.message << endl; };void Moe::show_curly(class Curly curly) { cout << curly.message << endl; };int main(void){   class Moe moe("nuck...");   class Curly curly("whoop...");    moe.show_message();   moe.show_curly(curly);   curly.show_message();   curly.show_moe(moe);}

Define friend function for <<

#include <iostream>#include <cstring>#include <cstdlib>using namespace std;class StringClass {  char *p;  int len;public:  StringClass(char *ptr);  ~StringClass() {     delete [] p;  }  friend ostream &operator<<(ostream &stream, StringClass &ob);};StringClass::StringClass(char *ptr){  len = strlen(ptr)+1;  p = new char [len];  if(!p) {    cout << "Allocation error\n";    exit(1);  }  strcpy(p, ptr);}ostream &operator<<(ostream &stream, StringClass &ob){  stream << ob.p;    return stream;}int main(){  StringClass stringObject1("www.java2s.com"), stringObject2("www.java2s.com");  cout << stringObject1;  cout << endl << stringObject2 << endl;  return 0;}