std::list<T,Allocator>::assign
From cppreference.com
void assign( size_type count, const T& value ); | (1) | (constexpr since C++26) |
template<class InputIt > void assign( InputIt first, InputIt last ); | (2) | (constexpr since C++26) |
void assign(std::initializer_list<T> ilist ); | (3) | (since C++11) (constexpr since C++26) |
Replaces the contents of the container.
1) Replaces the contents with count copies of value value.
2) Replaces the contents with copies of those in the range
[first, last).This overload has the same effect as overload (1) if | (until C++11) |
This overload participates in overload resolution only if | (since C++11) |
If first or last is an iterator into *this, the behavior is undefined.
3) Replaces the contents with the elements from ilist.
All iterators, pointers and references to the elements of the container are invalidated.
Contents |
[edit]Parameters
| count | - | the new size of the container |
| value | - | the value to initialize elements of the container with |
| first, last | - | the pair of iterators defining the source range of elements to copy |
| ilist | - | std::initializer_list to copy the values from |
[edit]Complexity
1) Linear in count.
2) Linear in distance between first and last.
3) Linear in ilist.size().
[edit]Example
The following code uses assign to add several characters to a std::list<char>:
Run this code
#include <list>#include <iostream>#include <string> int main(){std::list<char> characters; auto print_list =[&](){for(char c : characters)std::cout<< c <<' ';std::cout<<'\n';}; characters.assign(5, 'a'); print_list(); conststd::string extra(6, 'b'); characters.assign(extra.begin(), extra.end()); print_list(); characters.assign({'C', '+', '+', '1', '1'}); print_list();}
Output:
a a a a a b b b b b b C + + 1 1
Defect reports
The following behavior-changing defect reports were applied retroactively to previously published C++ standards.
| DR | Applied to | Behavior as published | Correct behavior |
|---|---|---|---|
| LWG 320 | C++98 | the replacement operation was required to be implemented as erasing all existing elements followed by inserting the given elements | removed the requirement |
[edit]See also
(C++23) | assigns a range of values to the container (public member function) |
| assigns values to the container (public member function) |
