в 14:21, 25 мая 2010

2010-05-25T14:21:06Z

Admin: 1 версия: Импорт контента...

2010-05-25T10:28:26Z

1 версия: Импорт контента...

Новая страница

==Demonstrate a custom inserter and extractor for objects of type ThreeD.==

<source lang="cpp">
#include <iostream>
using namespace std;
class ThreeD {
int x, y, z;
public:
ThreeD(int a, int b, int c) { x = a; y = b; z = c; }
// Make the inserter and extractor friends of ThreeD.
friend ostream &operator<<(ostream &stream, const ThreeD &obj);
friend istream &operator>>(istream &stream, ThreeD &obj);
};
// ThreeD inserter. Display the X, Y, Z coordinates.
ostream &operator<<(ostream &stream, const ThreeD &obj)
{
stream << obj.x << ", ";
stream << obj.y << ", ";
stream << obj.z << "\n";
return stream;
}
// ThreeD extractor. Get three-dimensional values.
istream &operator>>(istream &stream, ThreeD &obj)
{
stream >> obj.x >> obj.y >> obj.z;
return stream;
}
int main()
{
ThreeD td(1, 2, 3);
cout << "The coordinates in td: " << td << endl;
cout << "Enter new three-d coordinates: ";
cin >> td;
cout << "The coordinates in td are now: " << td << endl;
return 0;
}

</source>

==Non-member functions are used to create custom inserters for three_d objects and to overload + for int + three_d.==

<source lang="cpp">
#include <iostream>
using namespace std;
class three_d {
int x, y, z;
public:
three_d() { x = y = z = 0; }
three_d(int i, int j, int k) { x = i; y = j; z = k; }
three_d operator+(three_d rh_op);
three_d operator+(int rh_op);
three_d operator-(three_d rh_op);
three_d operator=(three_d rh_op);
bool operator==(three_d rh_op);
three_d operator-();
friend ostream &operator<<(ostream &strm, three_d op);
friend three_d operator+(int lh_op, three_d rh_op);
};
three_d three_d::operator+(three_d rh_op)
{
three_d temp;
temp.x = x + rh_op.x;
temp.y = y + rh_op.y;
temp.z = z + rh_op.z;
return temp;
}
three_d three_d::operator+(int rh_op)
{
three_d temp;
temp.x = x + rh_op;
temp.y = y + rh_op;
temp.z = z + rh_op;
return temp;
}
three_d three_d::operator-(three_d rh_op)
{
three_d temp;
temp.x = x - rh_op.x;
temp.y = y - rh_op.y;
temp.z = z - rh_op.z;
return temp;
}
three_d three_d::operator-()
{
three_d temp;
temp.x = -x;
temp.y = -y;
temp.z = -z;
return temp;
}
three_d three_d::operator=(three_d rh_op)
{
x = rh_op.x;
y = rh_op.y;
z = rh_op.z;
return *this;
}
bool three_d::operator==(three_d rh_op)
{
if( (x == rh_op.x) && (y == rh_op.y) && (z == rh_op.z) )
return true;
return false;
}
ostream &operator<<(ostream &strm, three_d op) {
strm << op.x << ", " << op.y << ", " << op.z << endl;
return strm;
}
three_d operator+(int lh_op, three_d rh_op) {
three_d temp;
temp.x = lh_op + rh_op.x;
temp.y = lh_op + rh_op.y;
temp.z = lh_op + rh_op.z;
return temp;
}
int main()
{
three_d objA(1, 2, 3), objB(10, 10, 10), objC;
cout << "This is objA: " << objA;
cout << "This is objB: " << objB;
objC = -objA;
cout << "This is -objA: " << objC;
objC = objA + objB;
cout << "objA + objB: " << objC;
objC = objA - objB;
cout << "objA - objB: " << objC;
objC = objA + 10;
cout << "objA + 10: " << objC;
objC = 100 + objA;
cout << "100 + objA: " << objC;
if(objA == objB)
cout << "objA is equal to objB.\n";
else
cout << "objA is not equal to objB.\n";
return 0;
}

</source>

==Overloading operator==

<source lang="cpp">
#include <iostream>
#include <string.h>
using namespace std;
class String
{
public:
String();
String(const char *const);
String(const String &);
~String();
char & operator[](int offset);
char operator[](int offset) const;
String operator+(const String&);
void operator+=(const String&);
String & operator= (const String &);
friend ostream& operator<<( ostream& theStream,String& theString);
int GetLen()const { return itsLen; }
const char * GetString() const { return itsString; }
private:
String (int);
char * itsString;
unsigned short itsLen;
};
String::String(){
itsString = new char[1];
itsString[0] = "\0";
itsLen=0;
}
String::String(int len)
{
itsString = new char[len+1];
for (int i = 0; i<=len; i++)
itsString[i] = "\0";
itsLen=len;
}
String::String(const char * const cString)
{
itsLen = strlen(cString);
itsString = new char[itsLen+1];
for (int i = 0; i<itsLen; i++)
itsString[i] = cString[i];
itsString[itsLen]="\0";
}
String::String (const String & rhs)
{
itsLen=rhs.GetLen();
itsString = new char[itsLen+1];
for (int i = 0; i<itsLen;i++)
itsString[i] = rhs[i];
itsString[itsLen] = "\0";
}
String::~String ()
{
delete [] itsString;
itsLen = 0;
}
String& String::operator=(const String & rhs)
{
if (this == &rhs)
return *this;
delete [] itsString;
itsLen=rhs.GetLen();
itsString = new char[itsLen+1];
for (int i = 0; i<itsLen;i++)
itsString[i] = rhs[i];
itsString[itsLen] = "\0";
return *this;
}
char & String::operator[](int offset){
if (offset > itsLen)
return itsString[itsLen-1];
else
return itsString[offset];
}
char String::operator[](int offset) const
{
if (offset > itsLen)
return itsString[itsLen-1];
else
return itsString[offset];
}
String String::operator+(const String& rhs)
{
int totalLen = itsLen + rhs.GetLen();
String temp(totalLen);
int i, j;
for (i = 0; i<itsLen; i++)
temp[i] = itsString[i];
for (j = 0; j<rhs.GetLen(); j++, i++)
temp[i] = rhs[j];
temp[totalLen]="\0";
return temp;
}
void String::operator+=(const String& rhs)
{
unsigned short rhsLen = rhs.GetLen();
unsigned short totalLen = itsLen + rhsLen;
String temp(totalLen);
int i, j;
for (i = 0; i<itsLen; i++)
temp[i] = itsString[i];
for (j = 0, i = 0; j<rhs.GetLen(); j++, i++)
temp[i] = rhs[i-itsLen];
temp[totalLen]="\0";
*this = temp;
}
ostream& operator<< ( ostream& theStream,String& theString)
{
theStream << theString.itsString;
return theStream;
}
int main()
{
String theString("Hello world.");
cout << theString;
return 0;
}

</source>

==Overload ostream and istream==

<source lang="cpp">
#include <iostream>
#include <cstring>
using namespace std;
class inventory {
char item[40]; // name of item
int onhand; // number on hand
double cost; // cost of item
public:
inventory(char *i, int o, double c)
{
strcpy(item, i);
onhand = o;
cost = c;
}
friend ostream &operator<<(ostream &stream, inventory ob);
friend istream &operator>>(istream &stream, inventory &ob);
};
ostream &operator<<(ostream &stream, inventory ob)
{
stream << ob.item << ": " << ob.onhand;
stream << " on hand at $" << ob.cost << "\n";
return stream;
}
istream &operator>>(istream &stream, inventory &ob)
{
cout << "Enter item name: ";
stream >> ob.item;
cout << "Enter number on hand: ";
stream >> ob.onhand;
cout << "Enter cost: ";
stream >> ob.cost;
return stream;
}
int main()
{
inventory ob("hammer", 4, 12.55);
cout << ob;
cin >> ob;
cout << ob;
return 0;
}

</source>

==Override and input output stream operator==

<source lang="cpp">
#include <iostream>
#include <string.h>
using namespace std;
class Employee
{
public:
Employee(void) {};
Employee(char *name, char sex, int age, char *phone)
{
strcpy(Employee::name, name);
Employee::sex = sex;
Employee::age = age;
strcpy(Employee::phone, phone);
};
friend ostream &operator<<(ostream &cout, Employee emp);
friend istream &operator>>(istream &stream, Employee &emp);
private:
char name[256];
char phone[64];
int age;
char sex;
};
ostream &operator<<(ostream &cout, Employee emp)
{
cout << "Name: " << emp.name << "\tSex: " << emp.sex;
cout << "\tAge: " << emp.age << "\tPhone: " << emp.phone << endl;
return cout;
}

istream &operator>>(istream &stream, Employee &emp)
{
cout << "Enter Name: ";
stream >> emp.name;
cout << "Enter Sex: ";
stream >> emp.sex;
cout << "Enter Age: ";
stream >> emp.age;
cout << "Enter Phone: ";
stream >> emp.phone;
return stream;
}
int main(void)
{
Employee worker;
cin >> worker;
cout << worker ;
}

</source>

← Предыдущая	Версия 14:21, 25 мая 2010
(нет различий)

C++/Overload/Inserter Extractor - История изменений

в 14:21, 25 мая 2010

Admin: 1 версия: Импорт контента...