C++/Overload/Unary Operator

Overload a unary operator.

<source lang="cpp">

1. include <iostream>

using namespace std; class MyClass {

 int x, y, z; 

public:

 MyClass() { 
    x = y = z = 0; 
 }
 MyClass(int i, int j, int k) {
    x = i; 
    y = j; 
    z = k; 
 }
 MyClass operator+(MyClass op2); 
 MyClass operator=(MyClass op2); 
 MyClass operator++();           
 void show() ;

} ; MyClass MyClass::operator+(MyClass op2) {

 MyClass temp;
 temp.x = x + op2.x; 
 temp.y = y + op2.y; 
 temp.z = z + op2.z; 
 return temp;

} MyClass MyClass::operator=(MyClass op2) {

 x = op2.x; // These are integer assignments
 y = op2.y; // and the = retains its original
 z = op2.z; // meaning relative to them.
 return *this;

} MyClass MyClass::operator++() {

 x++; // increment x, y, and z 
 y++; 
 z++;
 return *this;

} void MyClass::show() {

 cout << x << ", ";
 cout << y << ", ";
 cout << z << endl;

} int main() {

 MyClass a(1, 2, 3), b(10, 10, 10), c;
 a.show();
 b.show();
 c = a + b;     
 c.show();
 c = a + b + c; 
 c.show();
 c = b = a;     
 c.show();
 b.show();
 ++c;           
 c.show();
 return 0;

}

 </source>

Use a member function to overload the unary -.

<source lang="cpp">

1. 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>