int main()
{
Point *pointPtr = 0, p( 30, 50 );
Circle *circlePtr = 0, c( 2.7, 120, 89 );
cout << "Point p: " << p << "\nCircle c: " << c << '\n';
// Treat a Circle as a Point (see only the base class part)
pointPtr = &c; // assign address of Circle to pointPtr
cout << "\nCircle c (via *pointPtr): "
<< *pointPtr << '\n';
// Treat a Circle as a Circle (with some casting)
// cast base-class pointer to derived-class pointer
circlePtr = static_cast< Circle * >( pointPtr );
cout << "\nCircle c (via *circlePtr):\n" << *circlePtr
<< "\nArea of c (via circlePtr): "
<< circlePtr->area() << '\n';
// DANGEROUS: Treat a Point as a Circle
pointPtr = &p; // assign address of Point to pointPtr
// cast base-class pointer to derived-class pointer
circlePtr = static_cast< Circle * >( pointPtr );
cout << "\nPoint p (via *circlePtr):\n" << *circlePtr
<< "\nArea of object circlePtr points to: "
<< circlePtr->area() << endl;
return 0;
}
int main() {
Circle luke (10.5);
Circle wallace;
Circle lindsay = 6.2;
Circle owen(lindsay);
Circle isaac = luke + lindsay;
cout << "luke's area: " << luke.area() << "\n";
cout << "luke's circum: " << luke.circum() << "\n\n";
cout << "lindsay's area: " << lindsay.area() << "\n";
cout << "lindsay's circum: " << lindsay.circum() << "\n\n";
cout << "owen's area: " << owen.area() << "\n";
cout << "owen's circum: " << owen.circum() << "\n\n";
cout << "isaac's area: " << isaac.area() << "\n";
cout << "isaac's circum: " << isaac.circum() << "\n\n";
cout << "wallace's area: " << wallace.area() << "\n";
cout << "wallace's circum: " << wallace.circum() << "\n\n\n";
int a = 123;
int b = 456;
cout << "before swap: a = " << a << " and b = " << b << "\n";
swapInts(a, b);
cout << "after swap: a = " << a << " and b = " << b << "\n";
return 0;
}
JNIEXPORT jint JNICALL Native_StartCal(JNIEnv *env,jobject mc)
{
//int *str = (char*)env->GetStringUTFChars(data, NULL);
Circle* cir = new Circle(5);
cir->area();
LOGI("radius = %lf area=%lf",cir->radius,cir->area());
//cir.
return 0;
}
int main() {
Circle circle = Circle(5.3, 3.4, 9.88);
circle.showCircle();
cout << "Area = " << circle.area() << endl;
circle.move(12.09, 2);
// move()继承自Point，在父类中是公有的
// 公有继承下，move()在子类中是公有的
// 私有继承下，move()在子类中是私有的，main()中无法访问，但子类可以进行同名覆盖
circle.showCircle();
cout << "Area = " << circle.area() << endl;
return 0;
}
int main()
{
Circle cir;
cout << "圆的面积为：" << cir.area() << endl;
Cylinder cy;
cout << "圆柱体的表面积为：" << cy.area() << endl;
cout << "圆柱体的体积为：" << cy.volume() << endl;
return 0;
}
double circleoverlap(Circle c1,Circle c2)
{
double d = dis(c1.c,c2.c);
if(dcmp(c1.r-c2.r)<0)
swap(c1,c2);
if(dcmp(c1.r+c2.r-d)<=0)
return 0.0;
else if(dcmp(d+c2.r-c1.r)<=0)
return c2.area();
double theta1 = acos((c1.r*c1.r+d*d-c2.r*c2.r)/(2*d*c1.r));
double theta2 = acos((c2.r*c2.r+d*d-c1.r*c1.r)/(2*d*c2.r));
return c1.r*c1.r*theta1 + c2.r*c2.r*theta2 - d * c1.r * sin(theta1);
}
double volume() {return base.area() * height;}