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

From cppreference.com
< cpp‎ | container‎ | list
 
 
 
 
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 [firstlast). The behavior is undefined if either argument is an iterator into *this.

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 the initializer list 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 range to copy the elements from
ilist - 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>:

#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 defined as erasing all
existing elements followed by inserting the given elements
removed the definition

[edit] See also

constructs the list
(public member function) [edit]