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我必須開發一個組件，其中 將具有超過100,000個類的實例。並且我想根據特定類的不同標準（成員） 生成報告。例如， 具有數據字段ID， 名稱，地址，phoneno的員工類。報告wiil根據在不同的標準上維護一組獨特的元素C++ STL
- names_ascending
- names_descending
- addr_ascending
- phoneno_asceding
- unique_names
- unique_addr
- 聯合國 代ique_phoneno
每次調用的實例的運行時迭代非常慢，因爲它是大量實例的線性操作並且需要排序機制。
所以我已經存儲在不同的排序方式的容器中的每個實例的指針。但需要比所需更多的內存。請給我一個更好的方法來做到這一點。我已經發布了示例代碼片段，我遵循上面的實現。
class Employee
{
int m_id;
string m_name;
string m_addr;
string m_phone;
public:
Employee(int id, string name, string addr, string phone) :
m_id(id), m_name(name), m_addr(addr), m_phone(phone) { }
int id() const { return m_id; }
string name() const { return m_name; }
string addr() const { return m_addr; }
string phoneno() const { return m_phone; }
};
//custom predicate for std containers
struct IDComparator
{
bool operator() (const Employee* e1, const Employee* e2)
{
return e1->id() < e2->id();
}
};
struct NameComparator
{
bool operator() (const Employee* e1, const Employee* e2)
{
return e1->name() < e2->name();
}
}
struct AddressComparator
{
bool operator() (const Employee* e1, const Employee* e2)
{
return e1->addr() < e2->addr();
}
};
struct PhoneComparator
{
bool operator() (const Employee* e1, const Employee* e2)
{
return e1->phoneno() < e2->phoneno();
}
};
//Class which holds huge number of employee instances
class Dept
{
private:
typedef set<Employee*, IDComparator> EMPID; //unnique id
typedef EMPID::iterator EMPID_ITER;
typedef multiset<const Employee*, NameComparator> EMPNAME; // for sorted names
typedef EMPNAME::iterator NAME_ITER;
typedef multiset<const Employee*, AddressComparator> EMPADDR; // for sorted addr
typedef EMPADDR::iterator ADDR_ITER;
typedef multiset<const Employee*, PhoneComparator> EMPPHONE; // for sorted phoneno
typedef EMPPHONE::iterator PHONE_ITER;
private:
EMPID m_empids;
EMPNAME m_names ;
EMPADDR m_addr;
EMPPHONE m_phoneno;
public:
Dept() { }
~Dept() { //delete the instances of employees }
void add(Employee* e)
{
EMP_ITER iter = m_empids.insert(e).first;
const Employee* empptr = &*iter;
m_names.insert(empptr); // adds employee pointer to name multimap
m_addr.insert(empptr); // adds employee pointer to addr multimap
m_phoneno.insert(empptr); // adds employee pointer to phone multimap
}
void print_emp_dtls() const; //prints all the emp dtls iterating though EMPID
void print_unique_names() const; //iterate EMPNAME & use upperbound & lowerbound, prints unique names
void print_asc_name() const; //iterate EMPNAME & prints all names in ascending order
void print_desc_name() const; //back iterate EMPNAME & prints all names in descending order
void print_unique_adrr() const; //iterate EMPADDR & use upperbound & lowerbound, prints unique address
void print_asc_addr() const; //iterate EMPADDR & prints all addr in ascending order
void print_desc_addr() const; //back iterate EMPADDR & prints all address in descending order
void print_unique_phoneno() const; //iterate EMPPHONE & use upperbound & lowerbound,prints unique phoneno
void print_asc_phoneno() const; //iterate EMPPHONE & prints all phoneno in ascending order
void print_desc_phoneno() const; //back iterate EMPPHONE & prints all phoneno in };
+1提供代碼！ :) – Nim 2010-12-15 14:17:34
感謝球員....我熟悉STL，但新手到BOOST庫。這對我有用。 – Naveen 2010-12-15 14:23:02
@Naveen：那麼你應該接受正確的答案：這就是你如何說Stack Overflow的「感謝這個解決方案」！ – icecrime 2010-12-15 21:59:16