std::list<T,Allocator>::assign

 

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std::list

Member functions
list::list list::~list list::operator= list::assign list::assign_range (C++23)   list::get_allocator Element access list::front list::back Iterators list::beginlist::cbegin (C++11) list::endlist::cend (C++11) list::rbeginlist::crbegin (C++11) list::rendlist::crend (C++11) Capacity list::size list::empty list::max_size	Modifiers list::clear list::insert list::insert_range (C++23) list::emplace (C++11) list::erase list::push_front list::emplace_front (C++11) list::prepend_range (C++23) list::pop_front list::push_back list::emplace_back (C++11) list::append_range (C++23) list::pop_back list::resize list::swap Operations list::merge list::splice list::removelist::remove_if list::reverse list::unique list::sort
Non-member functions
operator==operator<=> (C++20) swap(std::list) erase(std::list)erase_if(std::list) (C++20)(C++20)	operator!=operator<operator>operator<=operator>= (until C++20)(until C++20)(until C++20)(until C++20)(until C++20)
Deduction guides(C++17)

 

void assign( size_type count, const T& value );	(1)
template< class InputIt > void assign( InputIt first, InputIt last );	(2)
void assign( std::initializer_list<T> ilist );	(3)	(since C++11)

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).

If either argument is an iterator into *this, the behavior is undefined.

This overload has the same effect as overload (1) if InputIt is an integral type.	(until C++11)
This overload participates in overload resolution only if InputIt satisfies LegacyInputIterator.	(since C++11)

3) Replaces the contents with the elements from ilist.

All iterators, pointers and references to the elements of the container are invalidated.

Parameters

count	-	the new size of the container
value	-	the value to initialize elements of the container with
first, last	-	the range to copy the elements from
ilist	-	std::initializer_list to copy the values from

Complexity

1) Linear in count.

2) Linear in distance between first and last.

3) Linear in ilist.size().

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();
 
    const std::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

See also

assign_range (C++23)	assigns a range of values to the container (public member function)
operator=	assigns values to the container (public member function)