std::char_traits<CharT>::assign

From cppreference.com
< cpp‎ | string‎ | char traits
(1)
static void assign( char_type& r, const char_type& a );
(until C++11)
static void assign( char_type& r, const char_type& a ) noexcept;
(since C++11)
(until C++17)
static constexpr void assign( char_type& r, const char_type& a ) noexcept;
(since C++17)
(2)
static char_type* assign( char_type* p, std::size_t count, char_type a );
(until C++20)
static constexpr char_type* assign( char_type* p,
                                    std::size_t count, char_type a );
(since C++20)

Assigns a character.

1) Assigns character a to character r.
2) Assigns character a to each character in count characters in the character sequence pointed to by p.

Parameters

a - character value to assign
r - character to assign to
p - pointer to a character sequence to assign to
count - the length of the character sequence

Return value

1) (none)
2) p

Complexity

1) Constant.
2) Linear in count.