std::flat_map<Key,T,Compare,KeyContainer,MappedContainer>::begin,std::flat_map<Key,T,Compare,KeyContainer,MappedContainer>::cbegin
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C++
Containers library
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| Sequence | ||||
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(C++26) | ||||
(C++26) | ||||
(C++11) | ||||
| Associative | ||||
| Unordered associative | ||||
(C++11) | ||||
(C++11) | ||||
(C++11) | ||||
(C++11) | ||||
| Adaptors | ||||
(C++23) | ||||
(C++23) | ||||
(C++23) | ||||
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(C++23) | ||||
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| Iterator invalidation | ||||
| Member function table | ||||
| Non-member function table |
std::flat_map
iterator begin()noexcept; | (1) | (since C++23) (constexpr since C++26) |
const_iterator begin()constnoexcept; | (2) | (since C++23) (constexpr since C++26) |
const_iterator cbegin()constnoexcept; | (3) | (since C++23) (constexpr since C++26) |
Returns an iterator to the first element of*this.
If*this is empty, the returned iterator will be equal toend().
Contents |
[edit]Return value
Iterator to the first element.
[edit]Complexity
Constant.
[edit]Example
Run this code
#include <iostream>#include <flat_map> int main(){std::flat_map<int,double> map{{4,4.13},{9,9.24},{1,1.09}}; for(auto it= map.cbegin(); it!= map.cend();++it)std::cout<<'['<< it->first<<"] = "<< it->second<<'\n'; // Unlike std::map's bidirectional iterators, the std::flat_map iterators// are random-access, so they can be used with the operator[]:auto it= map.cbegin();assert(it[0]== map[1]);assert(it[1]== map[4]);assert(it[2]== map[9]);}
Output:
[1] = 1.09[4] = 4.13[9] = 9.24
[edit]See also
| returns an iterator to the end (public member function)[edit] | |
(C++11)(C++14) | returns an iterator to the beginning of a container or array (function template)[edit] |
