1.c++STL中只有list自带了排序函数：
（1）.若list中存放的是int类型或者string类型，直接利用sort即可：
list <int> list1;
list1.sort();
此时默认为升序，若要使用降序，直接自定义cmp函数即可。
（2）.若存放的是结构体或其他指针类型，需要自己定义比较结构体：
struct student
{
int num;
};
struct node
{
bool operator()(student a,student b)
return a.num>b.num;//从大到小排序
};
list<student> list1;
list1.sort(node());
2.vector排序：
使用algorithm中的sort函数：
#include<iostream>
#include<vector>
#include<algorithm>
using namespace std;
int cmp(int a,int b){
return a > b;//按降序排序
}
int main(){
vector<int> vec;
vec.push_back(324);
vec.push_back(344);
vec.push_back(2134);
vec.push_back(23);
vec.push_back(12);
vec.push_back(134);
vec.push_back(987);
sort(vec.begin(),vec.end(),cmp);
vector<int>::iterator it;
for(it = vec.begin();it != vec.end();it++)
cout<<*it<<" ";
cout<<endl;
return 0;
}
3.STL中的set排序：其中set本身是自带排序的，默认按升序进行排序:
#include <iostream>
#include <set>
using namespace std;
int main()
{
set <int,less<int> > set1;//若使用less,则从小到大，若使用greater则从大到小。
set1.insert(20);
set1.insert(15);
set1.insert(0);
set1.insert(80);
set<int>::iterator cset=set1.begin();
while(cset!=set1.end())
{
cout<<*cset<<" ";
cset++;
}
int m;
cin>>m;
return 0;
}
若定义set中存储的为结构体：
#include <iostream>
#include <string>
#include <set>
using namespace std;
struct intComp {
bool operator() (const int& lhs, const int& rhs) const{
return lhs > rhs;
}
};
struct strComp
{
bool operator() (const string& str1, const string& str2) const {
return str1.length() < str2.length();
}
};
int main() {
int a[] = {10, 20, 30, 40, 50};
set<int, intComp> s1(a, a + 5);
for (auto it = s1.cbegin(); it != s1.cend(); it++)
{
cout << *it << " ";
}
cout << endl;
string b[] = {"apple", "banana", "pear", "orange", "strawberry"};
set<string, strComp > s2(b, b + 5);
for (auto it = s2.cbegin(); it != s2.cend(); it++)
{
cout << *it << " ";
}
cout << endl;
system("pause");
return 0;
}
4.STL中map：
由于在map中是由红黑树实现的所以自带生序排序（key）
#include <iostream>
#include <map>
#include <string>
using namespace std;
int main()
{
map <int,string,less<int> > map1;//使用less有小到大 greater由大到小
map1[1]="HZ";
map1[8]="yu";
map1[100]="rue";
map1[-10]="23";
map<int,string>::iterator cmap=map1.begin();
while(cmap!=map1.end())
{
cout<<cmap->first<<" ";
cmap++;
}
int m;
cin>>m;
return 0;
}
若存储的是结构体：
#include <iostream>
#include <map>
using namespace std;
struct student
{
int num;
};
bool operator <(student a,student b)
{
return a.num>b.num;//由大到小
}
int main()
{
map<student,int> map1;
student a;
a.num=100;
map1[a]=10;
student b;
b.num=1000;
map1[b]=11;
student c;
c.num=0;
map1[c]=102;
map<student,int> ::iterator st=map1.begin();
while(st!=map1.end())
{
cout<<(st->first).num<<" ";
st++;
}
int m;
cin>>m;
return 0;
}
map：（value）
#include <map>
#include <vector>
#include <algorithm>
#include <iostream>
using namespace std;
struct CmpByValue {
bool operator()(const pair<string,int> & lhs, const pair<string,int> & rhs)
{return lhs.second > rhs.second;}
};
void substrcount(string str)
{
map<string,int> substr;
string subs;
for(int i =1; i<str.size();i++)
for(int j =0; j<=str.size()-i;j++)
{
subs = str.substr(j,i);
if(substr.find(subs)==substr.end())
substr[subs] = 1;
else
substr[subs] = substr[subs]+1;
}
vector<pair<string,int>> counts(substr.begin(),substr.end());
sort(counts.begin(),counts.end(),CmpByValue());
cout<<(counts.begin()->first)<<endl;
cout<<counts.begin()->second<<endl;
}
原文地址：https://www.cnblogs.com/yan1/p/10582684.html