How can I get all the unique keys in a multimap

0 votes

I have a multimap and I want to save all of the unique keys in it in a vector.

multimap<char,int> mymm;
  multimap<char,int>::iterator it;
  char c;

  mymm.insert(pair<char,int>('x',50));
  mymm.insert(pair<char,int>('y',100));
  mymm.insert(pair<char,int>('y',150));
  mymm.insert(pair<char,int>('y',200));
  mymm.insert(pair<char,int>('z',250));
  mymm.insert(pair<char,int>('z',300));

How can I accomplish this? 

There is a method for counting the number of items with a key, but none for counting the number of unique keys in a multimap.

Added: By unique, I mean all the keys in the multimap just once - they can be duplicated or appear only once in the multimap.

So unique keys here are - xy and z

Jun 22 in C++ by Nicholas
• 6,240 points
41 views

1 answer to this question.

0 votes

This method worked for me.

for( multimap<char,int>::iterator it = mymm.begin(), end = mymm.end(); it != end; it = mymm.upper_bound(it->first))

  {
      cout << it->first << ' ' << it->second << endl;
  }
answered Jun 27 by Damon
• 4,960 points

Related Questions In C++

0 votes
0 answers

How can I get the maximum or minimum value in a vector?

In C++, how can I find the greatest or minimum value in a vector? Is it correct to assume that it would be similar with an array? Do I require an iterator?  I tried max element, but I kept receiving errors. vector<int>::const_iterator it; it = max_element(cloud.begin(), cloud.end()); error: request for ...READ MORE

Jun 27 in C++ by Nicholas
• 6,240 points
28 views
0 votes
0 answers

How can I get the size of a C++ function?

In C++, how can I find the size& ...READ MORE

Aug 5 in C++ by Nicholas
• 6,240 points
25 views
0 votes
0 answers

How can I get double quotes into a string literal?

I used the printf() command to produce the output seen below: printf("She said time flies like an arrow, ...READ MORE

Aug 5 in C++ by Nicholas
• 6,240 points
60 views
0 votes
0 answers

How can I terminate an infinite loop in Turbo C?

I get caught in an infinite loop.  How can I break this cycle?  Cntrl-C was attempted, however it had little effect.  I have no idea how to stop it. main() { ...READ MORE

Jul 13 in C++ by Nicholas
• 6,240 points
185 views
0 votes
1 answer

How do I reverse a C++ vector?

The algorithm header has a method std::reverse for this purpose. #include <vector> #include <algorithm> int main() { std::vector<int> ...READ MORE

answered Jun 27 in C++ by Damon
• 4,960 points
52 views
0 votes
1 answer

How to expose std::pair to python using boost::python?

The most simple example of exposing std::pair is: class_<std::pair<int, int> ...READ MORE

answered Jun 20, 2019 in Python by SDeb
• 13,300 points
612 views
0 votes
1 answer

How to find out if an item is present in an std::vector?

The most straightforward solution is to count the total number of elements in the vector that have the specified value.  If the count is greater than zero, we've found our element.  This is simple to accomplish with the std::count function. #include <iostream> #include <vector> #include <algorithm> int main() { ...READ MORE

answered May 27 in Others by Damon
• 4,960 points
49 views
0 votes
1 answer

Syntax of priority queue

We must first include the queue header file in order to establish a priority queue in C++. #include <queue> Once we import this file, we ...READ MORE

answered May 31 in C++ by Damon
• 4,960 points
32 views
0 votes
1 answer

How can I convert a std::string to int?

There are some new convert methods in C++ that convert std::string to a numeric type. As an alternative to str.c str() atoi(str.c str()) atoi(str.c str() you can make use of std::stoi std::stoi ...READ MORE

answered Jun 1 in C++ by Damon
• 4,960 points
51 views
0 votes
1 answer

how could I use the power function in c/c++ without pow(), functions, or recursion

It is part of a series.  Replace pow() with the previous iteration's value. There is no need for code to call pow ().  Pow(x, 5 * I - 1) and pow(-1, I - 1) may be formed since both have an int exponent dependent on the iterator I from the previous loop iteration. Example: Let f(x, i) = pow(x, 5 * i ...READ MORE

answered Jun 21 in C++ by Damon
• 4,960 points
245 views
webinar REGISTER FOR FREE WEBINAR X
Send OTP
REGISTER NOW
webinar_success Thank you for registering Join Edureka Meetup community for 100+ Free Webinars each month JOIN MEETUP GROUP