运算符重载

分类： C++2014-02-19 11:00 27人阅读 评论(0) 收藏 编辑 删除

一元的：

//: C12:OverloadingUnaryOperators.cpp

// From Thinking in C++,2nd Edition

// (c) Bruce Eckel 2000

// Copyright notice in Copyright.txt

#include <iostream>

using namespace std;

// Non-member functions:

class Integer {

long i;

Integer* This() { return this; }

public:

Integer(long ll = 0) : i(ll) {}

// No side effects takes const& argument:

friend const Integer&

operator+(const Integer& a);

friend const Integer

operator-(const Integer& a);

friend const Integer

operator~(const Integer& a);

friend Integer*

operator&(Integer& a);

friend int

operator!(const Integer& a);

// Side effects have non-const& argument:

// Prefix:

friend const Integer&

operator++(Integer& a);

// Postfix:

friend const Integer

operator++(Integer& a,int);

// Prefix:

friend const Integer&

operator--(Integer& a);

// Postfix:

friend const Integer

operator--(Integer& a,int);

};

// Global operators:

const Integer& operator+(const Integer& a) {

cout << "+Integer\n";

return a; // Unary + has no effect

}

const Integer operator-(const Integer& a) {

cout << "-Integer\n";

return Integer(-a.i);

}

const Integer operator~(const Integer& a) {

cout << "~Integer\n";

return Integer(~a.i);

}

Integer* operator&(Integer& a) {

cout << "&Integer\n";

return a.This(); // &a is recursive!

}

int operator!(const Integer& a) {

cout << "!Integer\n";

return !a.i;

}

// Prefix; return incremented value

const Integer& operator++(Integer& a) {

cout << "++Integer\n";

a.i++;

return a;

}

// Postfix; return the value before increment:

const Integer operator++(Integer& a,int) {

cout << "Integer++\n";

Integer before(a.i);

a.i++;

return before;

}

// Prefix; return decremented value

const Integer& operator--(Integer& a) {

cout << "--Integer\n";

a.i--;

return a;

}

// Postfix; return the value before decrement:

const Integer operator--(Integer& a,int) {

cout << "Integer--\n";

Integer before(a.i);

a.i--;

return before;

}

// Show that the overloaded operators work:

void f(Integer a) {

+a;

-a;

~a;

Integer* ip = &a;

!a;

++a;

a++;

--a;

a--;

}

// Member functions (implicit "this"):

class Byte {

unsigned char b;

public:

Byte(unsigned char bb = 0) : b(bb) {}

// No side effects: const member function:

const Byte& operator+() const {

cout << "+Byte\n";

return *this;

}

const Byte operator-() const {

cout << "-Byte\n";

return Byte(-b);

}

const Byte operator~() const {

cout << "~Byte\n";

return Byte(~b);

}

Byte operator!() const {

cout << "!Byte\n";

return Byte(!b);

}

Byte* operator&() {

cout << "&Byte\n";

return this;

}

// Side effects: non-const member function:

const Byte& operator++() { // Prefix

cout << "++Byte\n";

b++;

return *this;

}

const Byte operator++(int) { // Postfix

cout << "Byte++\n";

Byte before(b);

b++;

return before;

}

const Byte& operator--() { // Prefix

cout << "--Byte\n";

--b;

return *this;

}

const Byte operator--(int) { // Postfix

cout << "Byte--\n";

Byte before(b);

--b;

return before;

}

};

void g(Byte b) {

+b;

-b;

~b;

Byte* bp = &b;

!b;

++b;

b++;

--b;

b--;

}

int main() {

Integer a;

f(a);

Byte b;

g(b);

} ///:~

二元的：

//: C12:Integer.h

// From Thinking in C++,2nd Edition

// (c) Bruce Eckel 2000

// Copyright notice in Copyright.txt

// Non-member overloaded operators

#ifndef INTEGER_H

#define INTEGER_H

#include <iostream>

// Non-member functions:

class Integer {

long i;

public:

Integer(long ll = 0) : i(ll) {}

// Operators that create new,modified value:

friend const Integer

operator+(const Integer& left,

const Integer& right);

friend const Integer

operator-(const Integer& left,

const Integer& right);

friend const Integer

operator*(const Integer& left,

const Integer& right);

friend const Integer

operator/(const Integer& left,

const Integer& right);

friend const Integer

operator%(const Integer& left,

const Integer& right);

friend const Integer

operator^(const Integer& left,

const Integer& right);

friend const Integer

operator&(const Integer& left,

const Integer& right);

friend const Integer

operator|(const Integer& left,

const Integer& right);

friend const Integer

operator<<(const Integer& left,

const Integer& right);

friend const Integer

operator>>(const Integer& left,

const Integer& right);

// Assignments modify & return lvalue:

friend Integer&

operator+=(Integer& left,

const Integer& right);

friend Integer&

operator-=(Integer& left,

const Integer& right);

friend Integer&

operator*=(Integer& left,

const Integer& right);

friend Integer&

operator/=(Integer& left,

const Integer& right);

friend Integer&

operator%=(Integer& left,

const Integer& right);

friend Integer&

operator^=(Integer& left,

const Integer& right);

friend Integer&

operator&=(Integer& left,

const Integer& right);

friend Integer&

operator|=(Integer& left,

const Integer& right);

friend Integer&

operator>>=(Integer& left,

const Integer& right);

friend Integer&

operator<<=(Integer& left,

const Integer& right);

// Conditional operators return true/false:

friend int

operator==(const Integer& left,

const Integer& right);

friend int

operator!=(const Integer& left,

const Integer& right);

friend int

operator<(const Integer& left,

const Integer& right);

friend int

operator>(const Integer& left,

const Integer& right);

friend int

operator<=(const Integer& left,

const Integer& right);

friend int

operator>=(const Integer& left,

const Integer& right);

friend int

operator&&(const Integer& left,

const Integer& right);

friend int

operator||(const Integer& left,

const Integer& right);

// Write the contents to an ostream:

void print(std::ostream& os) const { os << i; }

};

#endif // INTEGER_H ///:~

//: C12:Integer.cpp {O}

// From Thinking in C++,2nd Edition

// (c) Bruce Eckel 2000

// Copyright notice in Copyright.txt

// Implementation of overloaded operators

#include "Integer.h"

#include "../require.h"

const Integer

operator+(const Integer& left,

const Integer& right) {

return Integer(left.i + right.i);

}

const Integer

operator-(const Integer& left,

const Integer& right) {

return Integer(left.i - right.i);

}

const Integer

operator*(const Integer& left,

const Integer& right) {

return Integer(left.i * right.i);

}

const Integer

operator/(const Integer& left,

const Integer& right) {

require(right.i != 0,"divide by zero");

return Integer(left.i / right.i);

}

const Integer

operator%(const Integer& left,

const Integer& right) {

require(right.i != 0,"modulo by zero");

return Integer(left.i % right.i);

}

const Integer

operator^(const Integer& left,

const Integer& right) {

return Integer(left.i ^ right.i);

}

const Integer

operator&(const Integer& left,

const Integer& right) {

return Integer(left.i & right.i);

}

const Integer

operator|(const Integer& left,

const Integer& right) {

return Integer(left.i | right.i);

}

const Integer

operator<<(const Integer& left,

const Integer& right) {

return Integer(left.i << right.i);

}

const Integer

operator>>(const Integer& left,

const Integer& right) {

return Integer(left.i >> right.i);

}

// Assignments modify & return lvalue:

Integer& operator+=(Integer& left,

const Integer& right) {

if(&left == &right) {/* self-assignment */}

left.i += right.i;

return left;

}

Integer& operator-=(Integer& left,

const Integer& right) {

if(&left == &right) {/* self-assignment */}

left.i -= right.i;

return left;

}

Integer& operator*=(Integer& left,

const Integer& right) {

if(&left == &right) {/* self-assignment */}

left.i *= right.i;

return left;

}

Integer& operator/=(Integer& left,

const Integer& right) {

require(right.i != 0,"divide by zero");

if(&left == &right) {/* self-assignment */}

left.i /= right.i;

return left;

}

Integer& operator%=(Integer& left,

const Integer& right) {

require(right.i != 0,"modulo by zero");

if(&left == &right) {/* self-assignment */}

left.i %= right.i;

return left;

}

Integer& operator^=(Integer& left,

const Integer& right) {

if(&left == &right) {/* self-assignment */}

left.i ^= right.i;

return left;

}

Integer& operator&=(Integer& left,

const Integer& right) {

if(&left == &right) {/* self-assignment */}

left.i &= right.i;

return left;

}

Integer& operator|=(Integer& left,

const Integer& right) {

if(&left == &right) {/* self-assignment */}

left.i |= right.i;

return left;

}

Integer& operator>>=(Integer& left,

const Integer& right) {

if(&left == &right) {/* self-assignment */}

left.i >>= right.i;

return left;

}

Integer& operator<<=(Integer& left,

const Integer& right) {

if(&left == &right) {/* self-assignment */}

left.i <<= right.i;

return left;

}

// Conditional operators return true/false:

int operator==(const Integer& left,

const Integer& right) {

return left.i == right.i;

}

int operator!=(const Integer& left,

const Integer& right) {

return left.i != right.i;

}

int operator<(const Integer& left,

const Integer& right) {

return left.i < right.i;

}

int operator>(const Integer& left,

const Integer& right) {

return left.i > right.i;

}

int operator<=(const Integer& left,

const Integer& right) {

return left.i <= right.i;

}

int operator>=(const Integer& left,

const Integer& right) {

return left.i >= right.i;

}

int operator&&(const Integer& left,

const Integer& right) {

return left.i && right.i;

}

int operator||(const Integer& left,

const Integer& right) {

return left.i || right.i;

} ///:~

//: C12:IntegerTest.cpp

// From Thinking in C++,2nd Edition

// (c) Bruce Eckel 2000

// Copyright notice in Copyright.txt

//{L} Integer

#include "Integer.h"

#include <fstream>

using namespace std;

ofstream out("IntegerTest.out");

void h(Integer& c1,Integer& c2) {

// A complex expression:

c1 += c1 * c2 + c2 % c1;

#define TRY(OP) \

out << "c1 = "; c1.print(out); \

out << ",c2 = "; c2.print(out); \

out << "; c1 " #OP " c2 produces "; \

(c1 OP c2).print(out); \

out << endl;

TRY(+) TRY(-) TRY(*) TRY(/)

TRY(%) TRY(^) TRY(&) TRY(|)

TRY(<<) TRY(>>) TRY(+=) TRY(-=)

TRY(*=) TRY(/=) TRY(%=) TRY(^=)

TRY(&=) TRY(|=) TRY(>>=) TRY(<<=)

// Conditionals:

#define TRYC(OP) \

out << "c1 = "; c1.print(out); \

out << ",c2 = "; c2.print(out); \

out << "; c1 " #OP " c2 produces "; \

out << (c1 OP c2); \

out << endl;

TRYC(<) TRYC(>) TRYC(==) TRYC(!=) TRYC(<=)

TRYC(>=) TRYC(&&) TRYC(||)

}

int main() {

cout << "friend functions" << endl;

Integer c1(47),c2(9);

h(c1,c2);

} ///:~