Multimap?

[john5632]

Hi, I am using multimap and key value can be duplicates. I can find first key value using find() function. But how to get next duplicate key value?

[Niklas L]

Which multimap implementation are you talking about?

[Resmi Anna]

multimap<string, string> mymap;
string strKey;

:
:

multimap<string, string>::iterator it;
:
it = mymap.find( strKey );
if(it != mymap.end())
{
do
{
cout << strKey << " = " << it->second << "\n";
it++;
}
while( it != mymap.upper_bound( strKey ));
}

[ThatsAlok]

cppreference.com

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[Stephen Hewitt]

Try something like this:

// MultiMap.cpp : Defines the entry point for the console application.
//

#include "stdafx.h"
#include <iostream>
#include <string>
#include <map>

void Go()
{
using namespace std;

typedef multimap<int, string> Tmm;
typedef Tmm::value\_type TmmVal;
typedef Tmm::const\_iterator TmmIt;
Tmm mm;

mm.insert(TmmVal(1, "One"));
mm.insert(TmmVal(1, "Single"));
mm.insert(TmmVal(2, "Two"));
mm.insert(TmmVal(2, "1+1"));
mm.insert(TmmVal(2, "Duo"));
mm.insert(TmmVal(3, "Three"));

pair<TmmIt, TmmIt> ip = mm.equal\_range(2);
for (TmmIt it=ip.first; it!=ip.second; ++it)
{
	cout << it->first << " : " << it->second << endl;
}

}

int main(int argc, char* argv[])
{
Go();

return 0;

}

Output is:

2 : Two
2 : 1+1
2 : Duo

Steve

[Stephen Hewitt]

This is inefficient. Why calculate the upper bound each loop?

Steve

[Stephen Hewitt]

I assume any standard compliant one will do.

Steve

[Niklas L]

I can see no standard compliance requirements in the original post, but your assumptions seem right.