我已经通过了所有与静态成员变量相关的线程,但不幸的是,这无法帮助我找出原因。C++类静态成员变量错误
这是问题:
1)定义一个类名称DVD_DB。包括以下成员。
DATA MEMBERS:
Name of DVD – private character array, size 10
Price – private double variable
Quantity – private int variable
A private static int variable to keep track of how many DVD have been created so far.
MEMBER FUNCTIONS:
To assign initial values
To set price and quantity
To get price and quantity
To Print DVD
To display how many DVD has been created so far.
在主要功能使用DVD阵列和显示DVD商店。即用户可以选择购买DVD &, 当DVD出售数量下降。
和,我已经写了这个代码来解决它。但在构建此代码时遇到问题。编译器说对我使用静态变量cnt的每一处都有未定义的引用。还有一个问题,因为我想最初将cnt设置为0,因为它是私有变量,所以要怎么做?
可以做些什么来解决未定义的参考问题?
class dvd_db{
private:
string name;
float price;
int quantity;
static int cnt;
public:
dvd_db()
{
name="";
price=0;
quantity=0;
cnt++; //to count the total number of dvds
}
dvd_db(string str,float p,int q)
{
name = str;
price = p;
quantity = q;
// cnt=0;
cnt+=q;
}
void set_name(string str)
{
name = str;
}
string get_name(void)
{
return name;
}
void set_price(float p)
{
price = p;
}
float get_price(void)
{
return price;
}
void set_quantity(int q)
{
quantity = q;
cnt+=q;
}
int get_quantity(void)
{
return quantity;
}
void show_info(void)
{
cout<<"Name if the DVD: "<<name<<endl;
cout<<"Price: "<<price<<endl;
cout<<"Available Quantity: "<<quantity<<endl;
}
void total(void)
{
cout<<"Total number of dvd is: "<<cnt<<endl;
}
void buy(void)
{
if(quantity>0){
quantity--;
cnt--;
cout<<"Thanks for purchasing this item"<<endl;
}
else
cout<<"This Item can not be bought."<<endl;
}
};
//dvd_db::cnt=0;
int main()
{
dvd_db dvd[3];
int i,j,k,n;
dvd[0].set_name("A Beautiful Mind");
dvd[0].set_price(50.00);
dvd[0].set_quantity(10);
dvd[1].set_name("October Sky");
dvd[1].set_price(50.00);
dvd[1].set_quantity(15);
dvd[2].set_name("Shawshank Redemption");
dvd[2].set_price(50.00);
dvd[2].set_quantity(100);
cout<<"Welcome to Banani International Movie House"<<endl;
cout<<"Enter the serial no. to buy an item, -1 to view total no. of dvd(s), or enter 0 to quit."<<endl;
cout<<"Here is our collection:"<<endl<<endl<<endl<<endl;
for(i=0; i<3; i++){
cout<<"serial no. "<<i+1<<endl;
cout<<"------------------------------------"<<endl;
dvd[i].show_info();
}
cout<<"Enter: "<<endl;
while(cin>>n)
{
if(n==-1){
dvd[0].total();
cout<<"Enter: "<<endl;
continue;
}
dvd[n-1].buy();
cout<<"Enter: "<<endl;
}
return 0;
}
可能的重复[未定义引用静态类成员](http://stackoverflow.com/questions/272900/undefined-reference-to-static-class-member) – juanchopanza