std::basic

2024-07-16 11:40| 来源: 网络整理| 查看: 265

C++ Compiler support Freestanding and hosted Language Standard library Standard library headers Named requirements Feature test macros (C++20) Language support library Concepts library (C++20) Metaprogramming library (C++11) Diagnostics library General utilities library Strings library Containers library Iterators library Ranges library (C++20) Algorithms library Numerics library Localizations library Input/output library Filesystem library (C++17) Regular expressions library (C++11) Concurrency support library (C++11) Technical specifications Symbols index External libraries [edit] Strings library Null-terminated strings Byte strings Multibyte strings Wide strings Classes basic_string basic_string_view(C++17) char_traits [edit] std::basic_string Member functions basic_string::basic_string basic_string::~basic_string basic_string::operator= basic_string::assign basic_string::assign_range(C++23) basic_string::get_allocator Element access basic_string::at basic_string::operator[] basic_string::front(DR*) basic_string::back(DR*) basic_string::data basic_string::c_str basic_string::operator basic_string_view(C++17) Iterators basic_string::beginbasic_string::cbegin(C++11) basic_string::endbasic_string::cend(C++11) basic_string::rbeginbasic_string::crbegin(C++11) basic_string::rendbasic_string::crend(C++11) Capacity basic_string::empty basic_string::sizebasic_string::length basic_string::max_size basic_string::reserve basic_string::capacity basic_string::shrink_to_fit(DR*) Modifiers basic_string::clear basic_string::insert basic_string::insert_range(C++23) basic_string::erase basic_string::push_back basic_string::pop_back(DR*) basic_string::append basic_string::append_range(C++23) basic_string::operator+= basic_string::replace basic_string::replace_with_range(C++23) basic_string::copy basic_string::resize basic_string::resize_and_overwrite(C++23) basic_string::swap Search basic_string::find basic_string::rfind basic_string::find_first_of basic_string::find_first_not_of basic_string::find_last_of basic_string::find_last_not_of Operations basic_string::compare basic_string::starts_with(C++20) basic_string::ends_with(C++20) basic_string::contains(C++23) basic_string::substr Constants basic_string::npos Non-member functions operator+ swap(std::basic_string) erase(std::basic_string)erase_if(std::basic_string)(C++20)(C++20) I/O operator getline Comparison operator==operator!=operatoroperator=operator(until C++20)(until C++20)(until C++20)(until C++20)(until C++20)(C++20) Numeric conversions stoistolstoll(C++11)(C++11)(C++11) stoulstoull(C++11)(C++11) stofstodstold(C++11)(C++11)(C++11) to_string(C++11) to_wstring(C++11) Literals operator""s(C++14) Helper classes hash(C++11) Deduction guides (C++17) [edit] basic_string& assign( size_type count, CharT ch ); (1) (constexpr since C++20) basic_string& assign( const basic_string& str ); (2) (constexpr since C++20) (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) (constexpr since C++20) basic_string& assign( basic_string&& str ) noexcept(/* see below */); (4) (since C++11) (constexpr since C++20) basic_string& assign( const CharT* s, size_type count ); (5) (constexpr since C++20) basic_string& assign( const CharT* s ); (6) (constexpr since C++20) template basic_string& assign( InputIt first, InputIt last ); (7) (constexpr since C++20) basic_string& assign( std::initializer_list ilist ); (8) (since C++11) (constexpr since C++20) template basic_string& assign( const StringViewLike& t ); (9) (since C++17) (constexpr since C++20) template

basic_string& assign( const StringViewLike& t,

size_type pos, size_type count = npos); (10) (since C++17) (constexpr since C++20)

Replaces the contents of the string.

1) Replaces the contents with count copies of character ch. 2) Replaces the contents with a copy of str. Equivalent to *this = str;. In particular, allocator propagation may take place.(since C++11) 3) Replaces the contents with a substring [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. 4) Replaces the contents with those of str using move semantics. Equivalent to *this = std::move(str). In particular, allocator propagation may take place. 5) Replaces the contents with copies of the characters in the range [s, s + count). This range can contain null characters. 6) Replaces the contents with those of null-terminated character string pointed to by s. The length of the string is determined by the first null character using Traits::length(s). 7) Replaces the contents with copies of the characters in the range [first, last). This overload does not participate in overload resolution if InputIt does not satisfy LegacyInputIterator.(since C++11) 8) Replaces the contents with those of the initializer list ilist. 9) Implicitly converts t to a string view sv as if by std::basic_string_view sv = t;, then replaces the contents with those of sv, as if by assign(sv.data(), sv.size()). This overload participates in overload resolution only if std::is_convertible_v is true and std::is_convertible_v is false. 10) Implicitly converts t to a string view sv as if by std::basic_string_view 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 participates in overload resolution only if std::is_convertible_v is true and std::is_convertible_v is false. Contents 1 Parameters 2 Return value 3 Complexity 4 Exceptions 5 Example 6 Defect reports 7 See also [edit] Parameters 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 ilist - std::initializer_list 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 LegacyInputIterator. [edit] Return value

*this

[edit] Complexity 1) Linear in count. 2) Linear in size of str. 3) Linear in count. 4) Constant. If alloc is given and alloc != other.get_allocator(), then linear. 5) Linear in count. 6) Linear in size of s. 7) Linear in distance between first and last. 8) Linear in size of ilist. 9) Linear in size of t. [edit] Exceptions 4) noexcept specification: noexcept(std::allocator_traits::

propagate_on_container_move_assignment::value ||

std::allocator_traits::is_always_equal::value)

If the operation would result in size() > max_size(), throws std::length_error.

If an exception is thrown for any reason, this function has no effect (strong exception safety guarantee).

[edit] Example Run this code #include #include #include int main() { std::string s; // assign(size_type count, CharT ch) s.assign(4, '='); std::cout

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