[英]Sorting vectors, that contains class objects, in C++ by class member's in order
我的目標是我想按照以下標准對向量進行排序; 我按“name”對整個向量進行了排序,當“name”相等時,我希望它按“surname”等排序。這是以下代碼:
下面我創建了一個 class;
class NotLearning {
public:
NotLearning(); // Constructor
int getID()const; // Function to used to initialise private variable "ID" of the class via the constructor.
int getDay()const; // Function to used to initialise private variable "day" of the class via the constructor.
int getYear()const; // Function to used to initialise private variable "year" of the class via the constructor.
double getAverage()const; // Function to used to initialise private variable "average" of the class via the constructor.
std::string getName()const; // Function to used to initialise private variable "name" of the class via the constructor.
std::string getSurname()const; // Function to used to initialise private variable "surname" of the class via the constructor.
std::string getCity()const; // Function to used to initialise private variable "city" of the class via the constructor.
std::string getMonth()const; // Function to used to initialise private variable "month" of the class via the constructor.
private:
int ID;
int day;
int year;
double average;
std::string name;
std::string surname;
std::string city;
std::string month;
};
我使用“ID”的 class 成員對包含 class 對象的向量進行排序,代碼如下:
void sortVectorByID(std::vector<NotLearning>& newClass)
{
std::sort(newClass.begin(), newClass.end(), cmp_by_id);
}
其中“ cmp_by_id ”是這樣定義的;
bool cmp_by_id(const NotLearning& one, const NotLearning& two) // compare classes inside the vector by checking the member of "ID".
{
return one.getID() < two.getID();
}
到目前為止,我已經成功地對向量進行了排序。 之后,我為我的目的實現了以下代碼;
void sortVectorByDetail(std::vector<NotLearning>& newClass)
{
std::sort(newClass.begin(), newClass.end(), cmp_by_detail);
}
其中“ cmp_by_detail ”是這樣定義的;
bool cmp_by_detail(const NotLearning& one, const NotLearning& two) // compare classes inside the vector by checking the members in order.
{
bool compare_result = cmp_by_id(one, two);
if (compare_result)
return compare_result;
compare_result = cmp_by_average(one, two);
if (compare_result)
return compare_result;
compare_result = cmp_by_name(one, two);
if (compare_result)
return compare_result;
compare_result = cmp_by_surname(one, two);
if (compare_result)
return compare_result;
compare_result = cmp_by_city(one, two);
if (compare_result)
return compare_result;
compare_result = cmp_by_day(one, two);
if (compare_result)
return compare_result;
compare_result = cmp_by_month(one, two);
if (compare_result)
return compare_result;
compare_result = cmp_by_year(one, two);
if (compare_result)
return compare_result;
return true;
}
我沒有給出 class 中的所有代碼,只是為了不分散你的注意力。 但是,如果您想查看所有代碼,我將GitHub留在這里。
我希望我能告訴你我需要什么。
如果您來到這條線,我非常感謝您節省您的時間^^。
祝你今天過得愉快。
編輯:我忘了提到當我調用sortVectorByDetail() function 時,我收到一個錯誤,提示調試斷言失敗無效比較器。 我也在下面離開了我過去調用這些函數的方式;
#include "LearningCpp.h"
int main()
{
srand((unsigned int)time(NULL));
std::vector<NotLearning> myClass;
fillVector(myClass);
showVector(myClass);
sortVectorByDetail(myClass);
showVector(myClass);
}
編輯:我現在通過對 cmp_by_detail 的function的以下實現解決了我的問題。 代碼在這里;
bool cmp_by_detail(const NotLearning& one, const NotLearning& two) {
if (one.getID() != two.getID())
{
return one.getID() < two.getID();
}
if (one.getAverage() != two.getAverage())
{
return one.getAverage() < two.getAverage();
}
if (one.getName() != two.getName())
{
return one.getName() < two.getName();
}
if (one.getSurname() != two.getSurname())
{
return one.getSurname() < two.getSurname();
}
if (one.getCity() != two.getCity())
{
return one.getCity() < two.getCity();
}
if (one.getDay() != two.getDay())
{
return one.getDay() < two.getDay();
}
if (one.getMonth() != two.getMonth())
{
return one.getMonth() < two.getMonth();
}
if (one.getYear() != two.getYear())
{
return one.getYear() < two.getYear();
}
return true;
}
實現一個 function 指針用於排序 function。
bool cmp(NotLearing a, NotLearning b)
{
if(a.getName()==b.getName())
return a.getSurname()<b.getSurname();
return a.getName<b.getName();
}
然后對你的向量進行排序
vector<NotLearning> v;
sort(v.begin(),v.end(),cmp);
我認為您應該檢查您在 cmp_by_detail 中使用的所有cmp_by_detail
。 function 中的某處斷言必須失敗。 看看這個以獲取更多信息
如果您想按字典順序比較相同 class 的兩個實例的某些“屬性”,您可以使用std::forward_as_tuple
。 這樣你的cmp_by_detail
實現就變成了......
bool cmp_by_detail (const NotLearning &one, const NotLearning &two)
{
return std::forward_as_tuple(one.getID(), one.getAverage(), one.getName(),
one.getSurname(), one.getCity(), one.getDay(),
one.getMonth(), one.getYear())
< std::forward_as_tuple(two.getID(), two.getAverage(), two.getName(),
two.getSurname(), two.getCity(), two.getDay(),
two.getMonth(), two.getYear());
}
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