C++ Using std::set<> in std::map<>

Question

I'd like to use std::set in std::map

I haven't much exp with std:: containers, so i am not sure if i am using it right. I am trying to process set of values and in each set is another set of values.

map<string, set<string> > data_map;

data_map["KEY1"].insert("VAL1");
data_map["KEY1"].insert("VAL2");

data_map["KEY2"].insert("VAL1");
data_map["KEY2"].insert("VAL3");

I get error here when i try to access set in map (inner for-cycle)

error: no match for call to ‘(std::set<std::basic_string<char> >) ()’|
error: no match for call to ‘(std::set<std::basic_string<char> >) ()’|


for( map<string, set<string> >::iterator mip = data_map.begin();mip != data_map.end(); ++mip) {
    for ( set<string>::iterator sit = mip->second().begin(); sit != mip->second().end(); ++sit )
        cout << *sit << endl;

}

Could you please tell me how i can iterate all values?

You just want second, not second() (it's a field of std::pair, not a method). Does that fix your issue? — Jeremy Roman
– Jeremy Roman, Commented Mar 11, 2014 at 13:48

Sebastian Hoffmann · Accepted Answer · 2014-03-11 13:49:13Z

3

mip->second().begin()

should be

mip->second.begin()

answered Mar 11, 2014 at 13:49

Sebastian Hoffmann

11.6k7 gold badges55 silver badges80 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

GreenOnBlack · Accepted Answer · 2014-03-11 15:26:20Z

2

You should use mip->second not mip->second(). I would recommed you to use auto in a for-each loop.

for(auto mip : data_map)
{  
    //Do another loop to get the values of your set, to get the set from the map use get<1>(mip);

}

Its better to read it that way and less space for errors.

edited Mar 11, 2014 at 15:26

answered Mar 11, 2014 at 13:53

GreenOnBlack

661 silver badge8 bronze badges

1 Comment

Jeremy Roman Over a year ago

If you're going to use auto, you're presumably in C++11. You might as well use the range-based for at that point.

Fred Larson · Accepted Answer · 2014-03-11 13:49:22Z

0

Don't call the set like a function.

for( map<string, set<string> >::iterator mip = lines.begin();mip != lines.end(); ++mip) {
    for ( set<string>::iterator sit = mip->second.begin(); sit != mip->second.end();
          ++sit )
        cout << *sit << endl;

answered Mar 11, 2014 at 13:49

Fred Larson

62.3k19 gold badges117 silver badges179 bronze badges

Collectives™ on Stack Overflow

C++ Using std::set<> in std::map<>

3 Answers 3

Comments

1 Comment

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

Comments

1 Comment

Comments

Your Answer

Sign up or log in

Post as a guest

Related