Difference between Override & Overload

Both of them only happen when difference function using same name.

• Overloading: picking a method signature at compile time based on the number and type of the arguments specified

  Overload--在compile时抓取function signature，每个function参数列表（参数数目和数量）不同，所以区别开来。

• Overriding: picking a method implementation at execution time based on the actual type of the target object (as opposed to the compile-time type of the expression)

  Override--在execution时选取不同的function来执行，注意这些function名称相同，参数列表相同。发生在类的继承中，子类function override夫类function，返回类型相同。

Example (with java):

class Base
{
    void foo(int x)
    {
        System.out.println("Base.foo(int)");
    }
		// this function will overload the function above
    void foo(double d)
    {
        System.out.println("Base.foo(double)");
    }
}

class Child extends Base
{		
  	// this function override the function in Base
    @Override void foo (int x)
    {
        System.out.println("Child.foo(int)");
    }
}

...

Base b = new Child();
b.foo(10); // Prints Child.foo(int)
b.foo(5.0); // Prints Base.foo(double)