c++ - How Can I get a range of values in a map for given lower bound and upper bound in an std::set? -

say have following code

#include <iostream> #include <set>  int main () {   std::set<int> myset;   int inf, sup;    inf = 25; sup = 60;   (int i=1; i<10; i++) myset.insert(i*10); // 10 20 30 40 50 60 70 80 90    return 0; } 

i trying figure out if standard library provides methods, or combination of methods allow me 2 iterators it_l, it_u such range [inf,sup] covered. i've tried use lower_bound, upper_bound i've misunderstood how works. idea avoiding write loops (because know write own function task, maybe there's alternative i'm not aware of).

update : examples of expected output (in example)

inf =25; sup = 60 expect {30,40,50,60}

if instead

inf=30; sup = 60 expect {30,40,50,60}

if

inf=25; sup = 65 expect {30,40,50,60}

apparently there's misunderstanding, or maybe it's me i'm not correctly expressing want do.

when inf , sup please intend them extreme values of real interval. once made such assumption want retrieve intersection between interval [inf,sup] , discrete set specified set objects. there contradiction between said , examples?

let a={10 20 30 40 50 60 70 80 90},b1=[25,60],b2=[30,60] , b3=[25,65]

for each i=1,2,3 intersection between a , bi gives i've said in examples.

this works fine me:

#include <iostream> #include <set>  template <typename t> std::pair<typename std::set<t>::const_iterator, typename std::set<t>::const_iterator> infsup(const std::set<t>& set, const t& inf, const t& sup) {   return std::make_pair(set.lower_bound(inf), set.upper_bound(sup)); }  int main () {   std::set<int> myset;   int inf, sup;    (int i=1; i<10; i++) myset.insert(i*10); // 10 20 30 40 50 60 70 80 90    (auto = infsup(myset, 30, 60); its.first != its.second; ++its.first)   {     std::cout << " " << *its.first; // 30 40 50 60   }   std::cout << std::endl;    (auto = infsup(myset, 25, 65); its.first != its.second; ++its.first)   {     std::cout << " " << *its.first; // 30 40 50 60   }   std::cout << std::endl;    return 0; } 

using lower_bound inf means start iterator point the first element not less inf, , fulfills condition want lower end of range.

using upper_bound sup means end iterator point _ first element greater sup_. note end iterator, in c++, points just past end of range, therefore sup included.

edit reflect discussion in comments (thanks @useless pointing out): note works fine empty result ranges, e.g.

• when both inf , sup less smallest element in set
• when both greater greatest element
• when there no elements within [inf, sup] (in example, inf=25, sup=29)

but if pick inf > sup returned iterators refer different elements, its.first > its.second, make for loops (as wrote them above) fail. ensure inf <= sup (just other for loop might writing).