std::basic_stringstream<CharT,Traits,Allocator>::str
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< cpp | io | basic stringstream
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basic_stringstream::str
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(1)
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 ) const;
(2)
(since C++20)
std::basic_string <CharT, Traits, SAlloc> str( const SAlloc& a ) const;
std::basic_string <CharT, Traits, Allocator> str() &&;
(3)
(since C++20)
void str( const std::basic_string <CharT, Traits, Allocator>& s );
(4)
template< class SAlloc >
void str( const std::basic_string <CharT, Traits, SAlloc>& s );
(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 >
void str( const StringViewLike& t );
(7)
(since C++26)
void str( const StringViewLike& t );
Manages the contents of the underlying string object.
1) Returns a copy of the underlying string. Equivalent to return rdbuf()->str();.
2) Returns a copy of the underlying string, using a as allocator. Equivalent to return rdbuf()->str(a);.
3) Returns a string move-constructed from the underlying string. Equivalent to return std::move(*rdbuf()).str();.
4,5) Replaces the contents of the underlying string. Equivalent to rdbuf()->str(s);.
6) Replaces the contents of the underlying string. Equivalent to rdbuf()->str(std::move(s));.
7) Replaces the contents of the underlying string. Equivalent to rdbuf()->str(t);.
This overload participates in overload resolution only if is_convertible_v<const T&, basic_string_view<charT, traits>> is true.
Contents
[edit] Parameters
s
-
new contents of the underlying string
t
-
an object (convertible to std::basic_string_view ) to use as the new contents of the underlying string
a
-
allocator used to construct the returned string
[edit] Return value
1,2) A copy of the underlying string object.
3) A string move-constructed from the underlying string object.
4-7) (none)
[edit] Notes
The copy of the underlying string returned by str is a temporary object that will be destructed at the end of the expression, so directly calling c_str() on the result of str() (for example in auto *ptr = out.str().c_str();) results in a dangling pointer.
| Feature-test macro | Value | Std | Feature |
|---|---|---|---|
__cpp_lib_sstream_from_string_view |
202306L |
(C++26) | Interfacing std::stringstream s with std::string_view , (7) |
[edit] Example
Run this code
#include <iostream> #include <sstream> int main() { int n; std::istringstream in; // could also use in("1 2") in.str("1 2"); in >> n; std::cout << "After reading the first int from \"1 2\", the int is " << n << ", str() = \"" << in.str() << "\"\n"; 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 ); 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"