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map question

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Join Date: Jun 2008

Posts: 92

Reputation: JackDurden is an unknown quantity at this point

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JackDurden JackDurden is offline

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Junior Poster in Training

map question

Aug 7th, 2009

How do you erase an element thats inside a map. Not the key but the element the key is pointing to? This doesnt seem to be doing what i want it to.

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
map<int, vector<int> > my_map;
map<int, vector<int> >::iterator it;
 
void erase(int num)
{
 
for(map::iterator item=my_map.begin();item != my_map.end())
	{
		if(it == num)
			my_map.erase(it++);
		else
		++it;
	}
}
map<int, vector<int> > my_map;
map<int, vector<int> >::iterator it;

void erase(int num)
{

for(map::iterator item=my_map.begin();item != my_map.end())
	{
		if(it == num)
			my_map.erase(it++);
		else
		++it;
	}
}

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Join Date: Dec 2006

Posts: 111

Reputation: jesseb07 is on a distinguished road

Solved Threads: 15

jesseb07

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Junior Poster

Re: map question

Aug 7th, 2009

looks like there's a couple things, I don't think that would even compile: comparing a map<int, vector<int> >::iterator to an int inside your loop doesn't seem safe to me. As well as not declaring the map type for your iterator.

anyway, see if this is a good starting point:

 Help with Code Tags 
 c++ Syntax (Toggle Plain Text) 
map<int, vector<int> > my_map; //I assume these are global or in a class, as you had it
map<int, vector<int> >::iterator it;
 
void erase(int num)
{
    for(it = my_map.begin(); it != my_map.end(); it++)
    {
        if((*it).first == num)
        {
            my_map.erase(it);
            break;
        }
    }
}
map<int, vector<int> > my_map; //I assume these are global or in a class, as you had it
map<int, vector<int> >::iterator it;

void erase(int num)
{
    for(it = my_map.begin(); it != my_map.end(); it++)
    {
        if((*it).first == num)
        {
            my_map.erase(it);
            break;
        }
    }
}