#include <iostream.h>#include <math.h>class Power{?public:??Power(int i){x=i;}??_______________________;?protected:??int x;};class Square:public Power{?public:??__________________________;??void display()??{???cout<<"x="<<x<<endl;???cout<<"x square="<<x*x<<endl;??}};class Cube:public Power{?________________________?};void fun(__________){?p.display();}int main(){?int m;?while(cin>>m)?{??Square squ(m);??Cube cub(m);??fun(squ);??fun(cub);?}?return 0;}?輸入輸入有多組測(cè)試數(shù)據(jù)，每行為一組測(cè)試數(shù)據(jù)，且只有一個(gè)正整數(shù)。輸出根據(jù)程序代碼輸出相應(yīng)的信息。樣例輸入123樣例輸出x=1x?square=1x=1x?cube=1x=2x?square=4x=2x?cube=8x=3x?square=9x=3x?cube=27請(qǐng)問(wèn)，Power類(lèi)中的語(yǔ)句中的Power(int){x=i}是什么，屬于哪個(gè)知識(shí)點(diǎn)呢？