C++ Tutorial/Operator Overloading/overload bracket operator
Содержание
- 1 Add a range check to for overloaded [] operator
- 2 design the operator[ ]( ) function in such a way that the [ ] can be used on both the left and right sides of an assignment statement.
- 3 Overload ( ) for Point
- 4 overloading ( ) for the loc class
- 5 Overload () operator for two values
- 6 The overloaded operator[ ]( ) function returns the value of the array as indexed by the value of its parameter.
Add a range check to for overloaded [] operator
<source lang="cpp">// A safe array example.
- include <iostream>
- include <cstdlib>
using namespace std;
class MyClass {
int a[3];
public:
MyClass(int i, int j, int k) {
a[0] = i;
a[1] = j;
a[2] = k;
}
int &operator[](int i);
};
// Provide range checking for MyClass. int &MyClass::operator[](int i) {
if(i<0 || i> 2) {
cout << "Boundary Error\n";
exit(1);
}
return a[i];
}
int main() {
MyClass ob(1, 2, 3); cout << ob[1]; // displays 2 cout << " "; ob[1] = 25; // [] appears on left cout << ob[1]; // displays 25 ob[3] = 44; // generates runtime error, 3 out-of-range return 0;
}</source>
design the operator[ ]( ) function in such a way that the [ ] can be used on both the left and right sides of an assignment statement.
<source lang="cpp">#include <iostream> using namespace std;
class MyClass {
int a[3];
public:
MyClass(int i, int j, int k) {
a[0] = i;
a[1] = j;
a[2] = k;
}
int &operator[](int i) { return a[i]; }
};
int main() {
MyClass ob(1, 2, 3); cout << ob[1]; // displays 2 cout << " "; ob[1] = 25; // [] on left of = cout << ob[1]; // now displays 25 return 0;
}</source>
Overload ( ) for Point
<source lang="cpp">#include <iostream> using namespace std; class Point {
int x, y;
public:
Point() {}
Point(int px, int py) {
x = px;
y = py;
}
void show() {
cout << x << " ";
cout << y << "\n";
}
Point operator+(Point op2);
Point operator()(int i, int j);
}; // Overload ( ) for Point. Point Point::operator()(int i, int j) {
x = i; y = j; return *this;
} // Overload + for Point. Point Point::operator+(Point op2) {
Point temp; temp.x = op2.x + x; temp.y = op2.y + y; return temp;
} int main() {
Point ob1(10, 20), ob2(1, 1); ob1.show(); ob1(7, 8); // can be executed by itself ob1.show(); ob1 = ob2 + ob1(10, 10); // can be used in expressions ob1.show(); return 0;
}</source>
10 20 7 8 11 11
overloading ( ) for the loc class
<source lang="cpp">#include <iostream> using namespace std;
class loc {
int longitude, latitude;
public:
loc() {}
loc(int lg, int lt) {
longitude = lg;
latitude = lt;
}
void show() {
cout << longitude << " ";
cout << latitude << "\n";
}
loc operator+(loc op2);
loc operator()(int i, int j);
};
// Overload ( ) for loc. loc loc::operator()(int i, int j) {
longitude = i; latitude = j; return *this;
}
// Overload + for loc. loc loc::operator+(loc op2) {
loc temp; temp.longitude = op2.longitude + longitude; temp.latitude = op2.latitude + latitude; return temp;
}
int main() {
loc ob1(10, 20), ob2(1, 1); ob1.show(); ob1(7, 8); // can be executed by itself ob1.show(); ob1 = ob2 + ob1(10, 10); // can be used in expressions ob1.show(); return 0;
}</source>
Overload () operator for two values
<source lang="cpp">#include<iostream.h> class Sample {
int A[10][10];
public:
int &operator()(int,int);
}; int &Sample::operator()(int x,int y) {
cout << "()"; return A[x][y];
} int main() {
Sample a;
int i,j;
for(i=0;i<10;i++){
for(j=0;j<10;j++)
a(i,j)=i+j;
for(i=0;i<10;i++)
cout<<a(i,1)<<" ";
}
cout<<endl;
}</source>
10 10
The overloaded operator[ ]( ) function returns the value of the array as indexed by the value of its parameter.
<source lang="cpp">#include <iostream> using namespace std;
class MyClass {
int a[3];
public:
MyClass(int i, int j, int k) {
a[0] = i;
a[1] = j;
a[2] = k;
}
int operator[](int i) { return a[i]; }
};
int main() {
MyClass ob(1, 2, 3); cout << ob[1]; // displays 2 return 0;
}</source>
