basic_string& assign( size_type count, CharT ch ); | (1) | |
basic_string& assign( const basic_string& str ); | (2) | |
(3) | ||
basic_string& assign( const basic_string& str, size_type pos, size_type count ); | (until C++14) | |
basic_string& assign( const basic_string& str, size_type pos, size_type count = npos); | (since C++14) | |
basic_string& assign( basic_string&& str ); | (4) | (since C++11) |
basic_string& assign( const CharT* s, size_type count ); | (5) | |
basic_string& assign( const CharT* s ); | (6) | |
template< class InputIt > basic_string& assign( InputIt first, InputIt last ); | (7) | |
basic_string& assign( std::initializer_list<CharT> ilist ); | (8) | (since C++11) |
basic_string& assign( std::basic_string_view<CharT, Traits> sv); | (9) | (since C++17) |
template < class T > basic_string& assign( const T& t, size_type pos, size_type count = npos); | (10) | (since C++17) |
Replaces the contents of the string.
count
copies of character ch
.str
.[pos, pos+count)
of str
. If the requested substring lasts past the end of the string, or if count == npos
, the resulting substring is [pos, str.size())
. If pos > str.size()
, std::out_of_range
is thrown. str
using move semantics. Equivalent to *this = std::move(str)
.count
characters of character string pointed to by s
. s
can contain null characters.s
. The length of the string is determined by the first null character. [first, last)
. This overload does not participate in overload resolution if InputIt
does not satisfy InputIterator
. (since C++11)
ilist
.sv
, as if by assign(sv.data(), sv.size())
t
to a string view sv
as if by std::basic_string_view<CharT, Traits> sv = t;
, then replaces the contents with the characters from the subview [pos, pos+count)
of sv
. If the requested subview lasts past the end of sv
, or if count == npos
, the resulting subview is [pos, sv.size())
. If pos > sv.size()
, std::out_of_range
is thrown. This overload only participates in overload resolution if std::is_convertible_v<const T&, std::basic_string_view<CharT, Traits>>
is true
and std::is_convertible_v<const T&, const CharT*>
is false
.count | - | size of the resulting string |
pos | - | index of the first character to take |
ch | - | value to initialize characters of the string with |
first, last | - | range to copy the characters from |
str | - | string to be used as source to initialize the characters with |
s | - | pointer to a character string to use as source to initialize the string with |
init | - | std::initializer_list to initialize the characters of the string with |
sv | - | std::basic_string_view to initialize the characters of the string with |
t | - | object (convertible to std::basic_string_view ) to initialize the characters of the string with |
Type requirements | ||
-InputIt must meet the requirements of InputIterator . |
*this
.
count
str
count
alloc
is given and alloc != other.get_allocator()
, then linear.count
s
first
and last
init
If an exception is thrown for any reason, this function has no effect (strong exception guarantee). (since C++11).
If the operation would result in size() > max_size()
, throws std::length_error
.
4) noexcept specification: noexcept |
(since C++11) (until C++17) |
4) noexcept specification: noexcept(std::allocator_traits<Allocator>::propagate_on_container_move_assignment::value | (since C++17) |
#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" }
Output:
==== Exemplary==Exemplary Exemplar C++ by example C-style C-style C-style string C-style
The following behavior-changing defect reports were applied retroactively to previously published C++ standards.
DR | Applied to | Behavior as published | Correct behavior |
---|---|---|---|
LWG 2063 | C++11 | non-normative note stated that swap is a valid implementation of move-assign | corrected to require move assignment |
constructs a basic_string (public member function) |
|
assigns values to the string (public member function) |
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