std::basic_istringstream<CharT,Traits,Allocator>::str - cppreference.com (original) (raw)

(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, 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( std::basic_string<CharT, Traits, Allocator>&& s ); (6) (since C++20)
template< class StringViewLike > void str( const StringViewLike& t ); (7) (since C++26)

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);.

  1. Replaces the contents of the underlying string. Equivalent to rdbuf()->str(std::move(s));.

  2. 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.

[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.

  1. 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::stringstreams with std::string_view, (7)

[edit] Example

#include #include   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"

[edit] See also

| | returns the underlying raw string device object (public member function) [edit] | | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | | replaces or obtains a copy of the associated character string (public member function of std::basic_stringbuf<CharT,Traits,Allocator>) [edit] |