How sort a unordered_map in alphabetical order?

[Ozzy69]

Hi, i want sort this unordered_map in alphabetical order with the function sort of the library algorithm using vectors. Look the my code! Help me!

#include <iostream>
#include <algorithm>
#include <string>
#include <unordered_map>

using namespace std;

int main()

{
unordered_map<string, int> h;


h["GG"] = 5;
h["HF"] = 1;
h["GL"] = 3;
h["SS"] = 6;


unordered_map<string, int>::iterator it;

for(it = h.begin(); it != h.end(); it++)
cout <<(*it).first << endl;

return 0;
}

[Peter87]

Loop through the unordered_map and add each key to the vector and then sort the vector after the loop. Or you could simply use std::map instead of std::unordered_map and it would always be sorted automatically.

[Gamer2015]

Hi, i want sort this unordered_map in alphabetical order with the function sort of the library algorithm using vectors. Look the my code! Help me!

Sort requires a container to have a random-access-operator, unordered map does not fulfill that condition so you can't sort it with sort.

You could, like Peter87 said, use std::map instead of std::unordered_map, then the keys will allways be sorted.
The standard sort condition is allways less-than, so the smallest element will be at the beginning.
If you want to have it sorted differently use the 3rd template parameter to give it a compare predicate, for example a function-object from the c++ standard.
The c++ standard provides a list of function-objects for comparison: http://www.cplusplus.com/reference/functional/

#include <iostream>
#include <algorithm>
#include <string>
#include <map>
#include <functional>

using namespace std;

int main()
{
    map<string, int, std::greater<std::string>> h;

    h["GG"] = 5;
    h["HF"] = 1;
    h["GL"] = 3;
    h["SS"] = 6;

    map<string, int>::iterator it;

    for(it = h.begin(); it != h.end(); it++)
        cout <<(*it).first << endl;

    return 0;
}

[Ozzy69]

Peter87, can you show me in code this that write.... I'm with difficults!!!

[kempofighter]

There is an example in the previous post so I'm not sure what you are asking Ozzy69. Unordered containers are named that way for a reason. They are not supposed to be sorted. They are typically implemented using hashing so that accessing and storing items is faster.