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Hi Team

I need help on my code, i must first find value associate with a key but not to duplicate. I tried on my void assign method to assign a value to it using map.Below is the example of what the program should do in c++ standard library

-2 -> 'A'
-1 -> 'A'
0 -> 'A'
1 -> 'B'
2 -> 'B'
3 -> 'A'
4 -> 'A'
5 -> 'A'

What I have tried:

<pre>#include <iostream>
#include <map>

class interval_map {
	friend void IntervalMapTest();
	V m_valBegin;
	typedef std::map<K,V> m_map;
	// constructor associates whole range of K with val
	interval_map(V const& val)
	: m_valBegin(val)

	// Assign value val to interval [keyBegin, keyEnd).
	// Overwrite previous values in this interval.
	// Conforming to the C++ Standard Library conventions, the interval
	// includes keyBegin, but excludes keyEnd.
	// If !( keyBegin < keyEnd ), this designates an empty interval,
	// and assign must do nothing.
void assign( K const& keyBegin, K const& keyEnd, V const& val )
    for( auto it = m_map.find( keyBegin ); * it != keyEnd; ++it )
        * it = val;

	// look-up of the value associated with key
	V const& operator[]( K const& key ) const {
		auto it=m_map.upper_bound(key);
		if(it==m_map.begin()) {
			return m_valBegin;
		} else {
			return (--it)->second;

int main()
    m_map map;
    m_map::iterator mpIter;
    int keyEnd, keyBegin;
    int count;
    // keep track of values with a std::set
    std::set<std::string> values;

    for(count = 0; count < 3; count++)
        cin >> key;
        cin >> value;

        auto found = map.find(key);

        if(found != map.end()) // key already in map
            continue; // don't add it again

        // now try to add it to the set
        // only add to the map if its value is not already in the set
            map.insert(std::make_pair(key, value));

    return 0;
Updated 9-Sep-22 5:11am
CPallini 9-Sep-22 7:50am    
Could you please detail your requirements?
It is not clear, for instance, if you can or cannot use the C++ standard libray.
(Actually it is not clear even what are you trying to do).
Richard MacCutchan 9-Sep-22 8:17am    
Why have you created a class that contains a std::map to implement a map? Why not just use std::map in the first place?
Gcobani Mkontwana 9-Sep-22 20:26pm    
@Richard MacCutchan basically i am implementing a logic on void assign method and below or after where the comment is written should look for a value associate with it not to duplicate it and use int main to run or compile it. std::map i must use it in order to achieve it. Perhaps on my code if could be shown where my issue is or if it could be revised it better. I can understand my mistake.

1 solution

You are already doing that in your code. Maybe you should read this : map::find - C++ Reference[^] because that is what you are doing currently and that is how you find values in a map.
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Gcobani Mkontwana 9-Sep-22 20:27pm    
@Rick York is possible to show me based on what i have written so far, so can understand where my problem was, i would appreciate that a lot and struggling
Rick York 9-Sep-22 21:27pm    
I have no idea where or what your problem is. I am just pointing out that find is the way to find a value associated with a key so read the documentation so that you understand that. You are already calling it twice in your code. Maybe you should consider using a debugger. I find them invaluable.

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