std::basic_string<CharT,Traits,Allocator>::assign

(1)

basic_string& assign( size_type count, CharT ch );

(C++20)

constexpr basic_string& assign( size_type count, CharT ch );

(C++20)

(2)

basic_string& assign( const basic_string& str );

(C++20)

constexpr basic_string& assign( const basic_string& str );

(C++20)

(3)

basic_string& assign( const basic_string& str, size_type pos, size_type count );

(C++14)

basic_string& assign( const basic_string& str, size_type pos, size_type count = npos);

(C++14)
(C++20)

constexpr basic_string& assign( const basic_string& str,                                 size_type pos, size_type count = npos);

(C++20)

(4)

basic_string& assign( basic_string&& str );

(C++11)
(C++17)

basic_string& assign( basic_string&& str ) noexcept(/* see below */);

(C++17)
(C++20)

constexpr basic_string& assign( basic_string&& str ) noexcept(/* see below */);

(C++20)

(5)

basic_string& assign( const CharT* s, size_type count );

(C++20)

constexpr basic_string& assign( const CharT* s, size_type count );

(C++20)

(6)

basic_string& assign( const CharT* s );

(C++20)

constexpr basic_string& assign( const CharT* s );

(C++20)

(7)

template< class InputIt > basic_string& assign( InputIt first, InputIt last );

(C++20)

template< class InputIt > constexpr basic_string& assign( InputIt first, InputIt last );

(C++20)

(8)

basic_string& assign( std::initializer_list<CharT> ilist );

(C++11)
(C++20)

constexpr basic_string& assign( std::initializer_list<CharT> ilist );

(C++20)

(9)

template < class T > basic_string& assign( const T& t );

(C++17)
(C++20)

template < class T > constexpr basic_string& assign( const T& t );

(C++20)

(10)

template < class T > basic_string& assign( const T& t, size_type pos, size_type count = npos);

(C++17)
(C++20)

template < class T > constexpr basic_string& assign( const T& t,                                 size_type pos, size_type count = npos);

(C++20)

1) ch count

2) str *this = str; (C++11)

3) str [pos, pos+count) count == npos [pos, str.size()) pos > str.size() std::out_of_range

4) str *this = std::move(str)

5) [s, s+count)

6) s Traits::length(s)

7) [first, last) InputIt LegacyInputIterator (C++11)

8) ilist

9) std::basic_string_view<CharT, Traits> sv = t; t sv assign(sv.data(), sv.size()) sv std::is_convertible_v<const T&, std::basic_string_view<CharT, Traits>> true std::is_convertible_v<const T&, const CharT*> false

10) std::basic_string_view<CharT, Traits> sv = t; t sv sv [pos, pos+count) sv count == npos [pos, sv.size()) pos > sv.size() std::out_of_range std::is_convertible_v<const T&, std::basic_string_view<CharT, Traits>> true std::is_convertible_v<const T&, const CharT*> false

count	-
pos	-
ch	-
first, last	-
str	-
s	-
ilist	-	std::initializer_list
t	-	(std::basic_string_view )

- `InputIt` LegacyInputIterator

*this

1) count

2) str

3) count

4) alloc alloc != other.get_allocator()

5) count

6) s

7) first last

8) ilist

() (C++11)

size() > max_size() std::length_error

4)

noexcept :

noexcept(std::allocator_traits<Allocator>::propagate_on_container_move_assignment::value  || std::allocator_traits<Allocator>::is_always_equal::value)

(C++17)

C++

DR
LWG 2063	C++11	non-normative note stated that swap is a valid implementation of move-assign	corrected to require move assignment
LWG 2579	C++11	`assign(const basic_string&)` doesn't propagate allocators	made to propagate allocators if needed
LWG 2946	C++17	`string_view` overload causes ambiguity in some cases	avoided by making it a template

Run this code

#include <iostream>
#include <iterator>
#include <string>

int main()
{
  std::string s;
  // assign(size_type count, CharT ch)
  s.assign(4, '=');
  std::cout << s << '\n'; // "===="
  
  std::string const c("Exemplary");
  // assign(basic_string const& str)
  s.assign(c);
  std::cout << c << "==" << s <<'\n'; // "Exemplary == Exemplary"

  // assign(basic_string const& str, size_type pos, size_type count)
  s.assign(c, 0, c.length()-1);
  std::cout << s << '\n'; // "Exemplar";

  // assign(basic_string&& str)
  s.assign(std::string("C++ by ") + "example");
  std::cout << s << '\n'; // "C++ by example"

  // assign(charT const* s, size_type count)
  s.assign("C-style string", 7);
  std::cout << s << '\n'; // "C-style"

  // assign(charT const* s)
  s.assign("C-style\0string");
  std::cout << s << '\n'; // "C-style"

  char mutable_c_str[] = "C-style string";
  // assign(InputIt first, InputIt last)
  s.assign(std::begin(mutable_c_str), std::end(mutable_c_str)-1);
  std::cout << s << '\n'; // "C-style string"

  // assign(std::initializer_list<charT> ilist)
  s.assign({ 'C', '-', 's', 't', 'y', 'l', 'e' });
  std::cout << s << '\n'; // "C-style"
}

:

====
Exemplary==Exemplary
Exemplar
C++ by example
C-style
C-style
C-style string
C-style

	`basic_string` () [edit]
operator=	() [edit]

cppreference.com

std::basic_string<CharT,Traits,Allocator>::assign