std::basic_stringstream<CharT,Traits,Allocator>:: str

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C++
Input/output library
std::basic_stringstream
(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 ) ; .
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 .

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

Return value

1,2) A copy of the underlying string object.
3) A string move-constructed from the underlying string object.
4-7) (none)

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 )

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"

See also

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