Effective C++ 筆記

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無參建構函式如何暴躁的構造.

先來看看標準的raw_memory :

void *intRawVar = operator new[](5*sizeof(int)); // create int raw memoryint *intVars = static_cast<int *>(intRawVar); // let int object to point this raw memoryfor(int i=0;i<5;i++){    new(&intVars[i])int(i*10);}for(int i=0;i<5;i++){    cout << intVars[i] <<endl;}operator delete[](intRawVar);

 

無參數如何暴力構造

#include <iostream>class EquipmentPiece{public:    EquipmentPiece(int IDNumber){        _var = IDNumber;    }    ~EquipmentPiece()    {    }private:    int _var;};using namespace std;int main(int argc, char *argv[]){    //<1>    //EquipmentPiece piece[10]; //error not default constructor    //<2>    typedef EquipmentPiece* PEP; //this method is ok,have resource leak & big memory allocation    PEP piece[10]; // create ten EquipmentPiece* pointer    //PEP *piece = new PEP[10]; // always is ok    for(int i=0;i<10;i++)    {        piece[i] = new EquipmentPiece(i);    }    for(int i=0;i<10;i++)    {        delete piece[i];    }    void *rawMemory = operator new[](10*sizeof(EquipmentPiece));    EquipmentPiece *pieces = static_cast<EquipmentPiece*>(rawMemory);    for(int i=0;i<10;i++)    {        new(&pieces[i])EquipmentPiece(i);    }    // release the EquipmentPiece object with reverse direction    for(int i=9;i >=0;--i)    {        pieces[i].~EquipmentPiece();    }    // release the raw memory    operator delete[](rawMemory);    return 0;}

 

Effective C++ 筆記