Supraîncărcarea Operatorilor în C++

Ce este Supraîncărcarea Operatorilor?

Permite definirea comportamentului operatorilor standard pentru tipuri definite de utilizator.

Exemplu Complet: Clasa Fractie

Copiază
1#include <iostream>
2using namespace std;
3
4class Fractie {
5private:
6    int numarator;
7    int numitor;
8    
9    void simplifica() {
10        int d = __gcd(abs(numarator), abs(numitor));
11        numarator /= d;
12        numitor /= d;
13        if (numitor < 0) {
14            numarator = -numarator;
15            numitor = -numitor;
16        }
17    }
18    
19public:
20    Fractie(int n = 0, int d = 1) : numarator(n), numitor(d) {
21        simplifica();
22    }
23    
24    // Operator + (membru)
25    Fractie operator+(const Fractie& other) const {
26        return Fractie(
27            numarator * other.numitor + other.numarator * numitor,
28            numitor * other.numitor
29        );
30    }
31    
32    // Operator - (membru)
33    Fractie operator-(const Fractie& other) const {
34        return Fractie(
35            numarator * other.numitor - other.numarator * numitor,
36            numitor * other.numitor
37        );
38    }
39    
40    // Operator * (membru)
41    Fractie operator*(const Fractie& other) const {
42        return Fractie(numarator * other.numarator, numitor * other.numitor);
43    }
44    
45    // Operator == (membru)
46    bool operator==(const Fractie& other) const {
47        return numarator == other.numarator && numitor == other.numitor;
48    }
49    
50    // Operator < (membru)
51    bool operator<(const Fractie& other) const {
52        return numarator * other.numitor < other.numarator * numitor;
53    }
54    
55    // Operator << (friend, pentru afișare)
56    friend ostream& operator<<(ostream& os, const Fractie& f) {
57        os << f.numarator;
58        if (f.numitor != 1) os << "/" << f.numitor;
59        return os;
60    }
61    
62    // Operator >> (friend, pentru citire)
63    friend istream& operator>>(istream& is, Fractie& f) {
64        char separator;
65        is >> f.numarator >> separator >> f.numitor;
66        f.simplifica();
67        return is;
68    }
69};
70
71int main() {
72    Fractie a(1, 2), b(1, 3);
73    
74    cout << a << " + " << b << " = " << (a + b) << endl;
75    cout << a << " - " << b << " = " << (a - b) << endl;
76    cout << a << " * " << b << " = " << (a * b) << endl;
77    cout << a << " == " << b << " : " << (a == b ? "true" : "false") << endl;
78    cout << a << " < " << b << " : " << (a < b ? "true" : "false") << endl;
79    
80    return 0;
81}

Operatori Care Nu Pot Fi Supraîncărcați

• •:: (scope resolution)
• •. (member access)
• •.* (member pointer access)
• •?: (ternary)
• •sizeof

Reguli Importante

1. •Nu poți schimba precedența sau asociativitatea
2. •Nu poți crea operatori noi
3. •Cel puțin un operand trebuie să fie de tip definit de utilizator