FreeBSD Manual Pages
std::basic_stringbuf::str(3) C++ Standard Libary std::basic_stringbuf::str(3) NAME std::basic_stringbuf::str - std::basic_stringbuf::str Synopsis std::basic_string<CharT, Traits, Allocator> str() const; (until C++20) std::basic_string<CharT, Traits, Allocator> str() const&; (since C++20) template<class SAlloc> std::basic_string<CharT, Traits, SAlloc> str( const SAlloc& a (2) (since C++20) ) const; std::basic_string<CharT, Traits, Allocator> str() &&; (3) (since C++20) void str( const std::basic_string<CharT, Traits, Allocator>& s (1) (4) ); template<class SAlloc> (5) (since C++20) void str( const std::basic_string<CharT, Traits, SAlloc>& s ); void str( std::basic_string<CharT, Traits, Allocator>&& s ); (6) (since C++20) template< class StringViewLike > (7) (since C++26) void str( const StringViewLike& t ); Gets and sets the underlying string. In the descriptions below, buf and mode are exposition-only data members of *this. 1) Creates and returns a std::basic_string object containing a copy of this std::basic_stringbuf's underlying character sequence. For input-only streams, the returned string contains the characters from the range [eback(), eg- ptr()). For input/output or output-only streams, contains the characters from pbase() to the last character in the sequence regardless of egptr() and epptr(). The member character sequence in a buffer open for writing can be over-allocated for efficiency purposes. In that case, only the initialized characters are returned: these characters are the ones that were obtained from the string ar- gument of the constructor, the string argument of the most recent call to a setter overload of str(), or from a write operation. A typical implementation that uses over-allocation maintains a high-watermark pointer to track the end of the initial- ized part of the buffer and this overload returns the characters from pbase() to the high-watermark pointer. Equivalent to return std::basic_string<CharT, Traits, (since C++20) Allocator>(view(), get_allocator());. 2) Same as (1), except that a is used to construct the returned std::basic_string. Equivalent to return std::basic_string<CharT, Traits, SAl- loc>(view(), a);. This overload participates in overload resolution only if SAlloc meets the requirements of Allocator. 3) Creates a std::basic_string object as if by move constructing it from *this's underlying character sequence in buf. buf may need to be adjusted to contain the same content as in (1) at first. After that, sets buf to empty and calls init_buf_ptrs(), then returns the std::basic_string object. 4) Replaces the underlying character sequence as if by buf = s, then calls init_buf_ptrs(). 5) Same as (4), except the type of s's allocator is not Allocator. This overload participates in overload resolution only if std::is_same_v<SAlloc, Allocator> is false. 6) Replaces the underlying character sequence as if by buf = std::move(s), then calls init_buf_ptrs(). 7) Implicitly converts t to a string view sv as if by std::ba- sic_string_view<CharT, Traits> sv = t;, then replaces the underlying character sequence as if by buf = sv, then calls init_buf_ptrs(). This overload participates in overload resolution only if std::is_convertible_v<const StringViewLike&, std::basic_string_view<CharT, Traits>> is true. Parameters s - a std::basic_string object holding the replacement character se- quence t - an object (convertible to std::basic_string_view) holding the replacement character sequence a - allocator to use for all memory allocations of the returned std::basic_string Return value 1-3) A std::basic_string object holding this buffer's underlying character sequence. 4-7) (none) Notes This function is typically accessed through std::ba- sic_istringstream::str(), std::basic_ostringstream::str(), or std::basic_stringstream::str(). Feature-test macro Value Std Fea- ture __cpp_lib_sstream_from_string_view 202306L (C++26) Interfacing string streams with std::string_view Example // Run this code #include <iostream> #include <sstream> int main() { int n; std::istringstream in; // could also use in("1 2") in.rdbuf()->str("1 2"); // set the get area in >> n; std::cout << "after reading the first int from \"1 2\", the int is " << n << ", str() = \"" << in.rdbuf()->str() << "\"\n"; // or in.str() std::ostringstream out("1 2"); out << 3; std::cout << "after writing the int '3' to output stream \"1 2\"" << ", str() = \"" << out.str() << "\"\n"; std::ostringstream ate("1 2", std::ios_base::ate); // C++11 ate << 3; std::cout << "after writing the int '3' to append stream \"1 2\"" << ", str() = \"" << ate.str() << "\"\n"; } Output: after reading the first int from "1 2", the int is 1, str() = "1 2" after writing the int '3' to output stream "1 2", str() = "3 2" after writing the int '3' to append stream "1 2", str() = "1 23" Defect reports The following behavior-changing defect reports were applied retroac- tively to previously published C++ standards. DR Applied to Behavior as published Correct behavior 1. overload (1) did not specify the content LWG 432 C++98 of the underlying character sequence both specified 2. overload (4) did not specify how the input and output sequences are initialized overload (4) set epptr() to point one past LWG 562 C++98 the last underlying epptr() can be set character if bool(mode & std::ios_base::out) be- yond that position == true See also gets or sets the contents of underlying string device object str (public member function of std::ba- sic_stringstream<CharT,Traits,Allocator>) view obtains a view over the underlying character sequence (C++20) (public member function) http://cppreference.com 2024.06.10 std::basic_stringbuf::str(3)
NAME | Synopsis | Parameters | Return value | Notes | Example | Output: | See also
Want to link to this manual page? Use this URL:
<https://man.freebsd.org/cgi/man.cgi?query=std::stringbuf::str&sektion=3&manpath=FreeBSD+Ports+15.1.quarterly>