這是上次PPT所應該講述的代碼內容。現在放上來，大家就應該清楚PPT未完成的部分所想要描述的技術了。PS：代碼中還是有些沒用的東西。
template?<typename?LeftExp,?typename?Op,?typename?RightExp>
struct?Expression?
{
????const?LeftExp?&?left;
????const?RightExp?&?right;
????
????Expression(const?LeftExp?&?_l,?const?RightExp?&?_r)?:?left(_l),?right(_r){}
????
????double?operator?[]?(int?index)?const?{
????????return?Op::eval(left[index],?right[index]);
????}
};
struct?EPLUS?{
????static?double?eval(double?a,?double?b)?{?return?a+b;}
};
class?Matrix?
{
private:
????int?M,N;
????double?*?element;
public:
????Matrix(int?m,?int?n):?M(m),N(n)?{
????????element?=?new?double[M*N];
????}
????~Matrix(){
????????if?(element)?{
????????????delete?[]element;
????????????element?=?0;
????????}
????}
????int?getM()?const?{?return?M;}
????int?getN()?const?{?return?N;}
????int?getSize()?const?{return?M*N;}
????
????double?&?operator?()(int?i,?int?j)?const?{?return?element[i*N+j];?}
????double?operator?[](int?index)?const?{return?element[index];?}
????
????template?<typename?Exp>
????Matrix?&?operator?=?(Exp?&?exp)?{????
????????int?size?=?M*N;
????????for?(int?i=0;i<size;i++)?{
????????????element[i]?=?exp[i];
????????}
????????return?*?this;
????}
template?<typename?LeftExp,?typename?RightExp>
inline?Expression<LeftExp,EPLUS,?RightExp>?operator?+?(const?LeftExp?&?a,?const?RightExp?&?b)?{?
????return?Expression<LeftExp,?EPLUS,?RightExp>(a,?b);
}
int?main()?{
????const?int?M=3,?N=4;
????Matrix?a(M,N),?b(M,N),?c(M,N);
????{
????????for?(int?i=0;i<M;i++)?
????????????for?(int?j=0;j<N;j++)?{
????????????????a(i,j)?=?i+j;
????????????????b(i,j)?=?i*j;
????????????????c(i,j)?=?0;
????????????}
????}
????c?=?a?+?b;
????return?0;
}