std::sort

场景:

1. 在使用sort排序时，有时候需要对对象的某个值进行排序，比如对类对象的某个id的int类型值或者bool类型值,其实bool类型值排序研究了半天。。

test_sort.cpp

#include <stdlib.h>
#include <string.h>
#include <string>
#include <vector>
#include <algorithm>
#include <iostream>

using namespace std;

template <typename t>
void Print (vector<t> array)
{
	int size = array.size();
	cout << "size: " << size << endl;
	for (int i = 0; i < size; ++i)
	{
		cout << array[i] << endl;
	}
}

class Data
{
	friend ostream &operator<<(ostream &output, const Data* data);
public:
	Data(){}
	~Data(){}
	int id_;
	bool is_deleted_;

};

ostream& operator<<( ostream& os,const Data* data)
{
	return os << data->id_ << ":" << data->is_deleted_;
}

void SortString()
{
	vector<string> array;
	array.push_back("abc");
	array.push_back("a");
	array.push_back("bc");
	array.push_back("h");

	//1.从小到大排序
	cout << "sort with from small to big" << endl;
	sort(array.begin(),array.end(),std::less<string>());
	Print(array);

	//1.从大到小排序
	cout << "sort with from big to small" << endl;
	sort(array.begin(),array.end(),std::greater<string>());
	Print(array);

}

void SortInt()
{
	vector<int> array;
	array.push_back(4);
	array.push_back(5);
	array.push_back(1);
	array.push_back(2);

	//1.从小到大排序
	cout << "sort with from small to big" << endl;
	sort(array.begin(),array.end(),std::less<int>());
	Print(array);

	//1.从大到小排序
	cout << "sort with from big to small" << endl;
	sort(array.begin(),array.end(),std::greater<int>());
	Print(array);

}

bool CompId(Data* first,Data* second)
{
	return first->id_ < second->id_;
}

bool CompBool(Data* first,Data* second)
{
	return first->is_deleted_ > second->is_deleted_;
}

void SortData()
{
	vector<Data*> array;
	Data *d1 = new Data();
	d1->id_ = 4;
	d1->is_deleted_ = true;

	Data *d2 = new Data();
	d2->id_ = 3;
	d2->is_deleted_ = false;

	Data *d3 = new Data();
	d3->id_ = 1;
	d3->is_deleted_ = true;

	Data *d4 = new Data();
	d4->id_ = 5;
	d4->is_deleted_ = false;

	array.push_back(d1);
	array.push_back(d2);
	array.push_back(d3);
	array.push_back(d4);
	//1.根据id_从小到大排序.
	sort(array.begin(),array.end(),CompId);
	Print(array);

	//1.根据is_deleted_排序,true在前面.
	sort(array.begin(),array.end(),CompBool);
	Print(array);

}

int main(int argc, char const *argv[])
{
	cout << "begin" << endl;
	SortInt();
	SortString();
	SortData();
	return 0;
}

输出:

begin
sort with from small to big
size: 4
1
2
4
5
sort with from big to small
size: 4
5
4
2
1
sort with from small to big
size: 4
a
abc
bc
h
sort with from big to small
size: 4
h
bc
abc
a
size: 4
1:1
3:0
4:1
5:0
size: 4
1:1
4:1
3:0
5:0