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#2
rjsp2017-04-17 15:23
ka k(num, password, money);
p=&k; return p; 返回局部临时变量的地址？  程序代码：#include <iostream> #include <string> class card { public: card( const std::string& num, const std::string& password, int money ) : num_(num), password_(password), money_(money) { ++g_count_; } card( const card& c ) : num_(c.num_), password_(c.password_), money_(c.money_) { ++g_count_; } ~card() { --g_count_; } void save_cash( double cash ) { money_ += cash; } double cash() const { return money_; } private: std::string num_; std::string password_; double money_; public: static size_t card_num() { return g_count_; } private: static size_t g_count_; }; size_t card::g_count_ = 0; using namespace std; card card_input( void ) { string num; string password; int money; cout << "input card num:"; cin >> num; cout << "input card password:"; cin >>password; cout << "input card cash:"; cin >> money; return card( num, password, money ); } int main( void ) { card c = card_input(); cout << "remaining cash: " << c.cash() << '\n'; double cash; cin >> cash; c.save_cash( cash ); cout << "remaining cash: " << c.cash() << '\n'; cin >> cash; c.save_cash( cash ); cout << "remaining cash: " << c.cash() << '\n'; cout << "Card number: " << card::card_num() << endl; return 0; } |
#include<iostream>
#include<string>
using namespace std;
class ka
{
string num;
string password;
double money;
static int count;
public:
ka(string num, string password, int money){this->num=num; this->password=password; this->money=money; count++;}
~ka(){count--;}
void xg(double cash){money+=cash;}
void showmoney(){cout<<"余额为:"<<money<<endl;}
static void show(){cout<<"已发卡:"<<count<<endl;}
};
int ka::count=0;
ka *sq()
{
ka *p;
string num, password;
int money;
cout<<"请输入卡号:";
cin>>num;
cout<<"请输入密码:";
cin>>password;
cout<<"请输入金额:";
cin>>money;
ka k(num, password, money);
p=&k;
return p;
}
int main()
{
ka *p;
p=sq();
double cash;
p->showmoney();
cout<<"改变余额:"<<endl;
cin>>cash;
p->xg(cash);
p->showmoney();
cout<<"再次改变余额:"<<endl;
cin>>cash;
p->xg(cash);
p->showmoney();
//p::show();
return 0;
}
执行代码后，改变余额余额没有正确的变化。
还有就是怎么用指针访问静态函数。
如果我用new怎么调用显示构造，还是不需要调用显示构造。