Namespaces
Variants

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

    From cppreference.com
    See More

    [edit template]
     
    C++
     
    Input/output library
     
    std::basic_stringstream
     
    (1)
    explicit basic_stringstream( std::ios_base::openmode mode = {{#pad:|27}} std::ios_base::in | std::ios_base::out );
    		 (until C++11)
    explicit basic_stringstream( std::ios_base::openmode mode );
    		 (since C++11)
    basic_stringstream() : basic_stringstream(std::ios_base::in | std::ios_base::out) {}
    		 (2) (since C++11)
    explicit basic_stringstream ( const std::basic_string<CharT, Traits, Allocator>& str, std::ios_base::openmode mode = std::ios_base::in | std::ios_base::out );
    		 (3)
    explicit basic_stringstream ( std::basic_string<CharT, Traits, Allocator>&& str, std::ios_base::openmode mode = std::ios_base::in | std::ios_base::out );
    		 (4) (since C++20)
    basic_stringstream( std::ios_base::openmode mode, const Allocator& a );
    		 (5) (since C++20)
    template< class SAlloc > basic_stringstream( const std::basic_string<CharT, Traits, SAlloc>& str, {{#pad:|18}} std::ios_base::openmode mode, const Allocator& a );
    		 (6) (since C++20)
    template< class SAlloc > basic_stringstream( const std::basic_string<CharT, Traits, SAlloc>& str, {{#pad:|18}} const Allocator& a ) : basic_stringstream(str, std::ios_base::in | std::ios_base::out, a) {}
    		 (7) (since C++20)
    template< class SAlloc > explicit basic_stringstream ( const std::basic_string<CharT, Traits, SAlloc>& str, std::ios_base::openmode mode = std::ios_base::in | std::ios_base::out );
    		 (8) (since C++20)
    template< class StringViewLike > explicit basic_stringstream ( const StringViewLike& t, std::ios_base::openmode mode = std::ios_base::in | std::ios_base::out );
    		 (9) (since C++26)
    template< class StringViewLike > basic_stringstream( const StringViewLike& t, {{#pad:|18}} std::ios_base::openmode mode, const Allocator& a );
    		 (10) (since C++26)
    template< class StringViewLike > basic_stringstream( const StringViewLike& t, const Allocator& a );
    		 (11) (since C++26)
    basic_stringstream( basic_stringstream&& other );
    		 (12) (since C++11)

    Constructs new string stream.

    Given

    • base_type as std::basic_iostream<CharT, Traits>, and
    • buf_type as std::basic_stringbuf<CharT, Traits, Allocator>,

    the std::basic_iostream base and the exposition-only data member sb are initialized as follows.

    Over
     load      		std::basic_iostream base sb
    (1) base_type(std::addressof(sb))[1] buf_type(mode)
    (2) buf_type(std::ios_base::in | std::ios_base::out)
    (3) buf_type(str, mode)
    (4) buf_type(std::move(str), mode)
    (5) buf_type(mode, a)
    (6) buf_type(str, mode, a)
    (7) buf_type(str, std::ios_base::in | std::ios_base::out, a)
    (8) buf_type(str, mode)
    (9) std::addressof(sb) {t, mode, Allocator()}
    (10) {t, mode, a}
    (11) {t, std::ios_base::in | std::ios_base::out, a}
    (12) move constructed from other's std::basic_iostream base move constructed from other.sb
    1. ↑ The std::basic_iostream base was intialized with base_type(&sb) (for overloads (1,3)) until C++11.
    8) This overload participates in overload resolution only if std::is_same_v<SAlloc, Allocator> is false.
    9-11) These overloads participate in overload resolution only if std::is_convertible_v<const StringViewLike&, std::basic_string_view<CharT, Traits>> is true.

    Parameters

    str - string to use as initial contents of the string stream
    t - an object (convertible to std::basic_string_view) to use as initial contents of the string stream
    a - allocator used for allocating the contents of the string stream
    mode - specifies stream open mode. It is a BitmaskType, the following constants are defined:
    Constant Explanation
    app seek to the end of stream before each write
    binary open in binary mode
    in open for reading
    out open for writing
    trunc discard the contents of the stream when opening
    ate seek to the end of stream immediately after open
    noreplace (C++23) open in exclusive mode
    other - another string stream to use as source

    Notes

    Construction of one-off basic_stringstream objects in a tight loop, such as when used for string conversion, may be significantly more costly than calling str() to reuse the same object.

    Feature-test macro Value Std Feature
    __cpp_lib_sstream_from_string_view 202306L (C++26) Interfacing std::stringstreams with std::string_view, (9-11)

    Example

    Run this code
    #include <iostream>
#include <sstream>

int main()
{
    // default constructor (input/output stream)
    std::stringstream buf1;
    buf1 << 7;
    int n = 0;
    buf1 >> n;
    std::cout << "buf1 = " << buf1.str() << " n = " << n << '\n';
    
    // input stream
    std::istringstream inbuf("-10");
    inbuf >> n;
    std::cout << "n = " << n << '\n';
    
    // output stream in append mode (C++11)
    std::ostringstream buf2("test", std::ios_base::ate);
    buf2 << '1';
    std::cout << buf2.str() << '\n';
}

    Output: 

    buf1 = 7 n = 7
n = -10
test1

    Defect reports

    The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

    DR Applied to Behavior as published Correct behavior
    P0935R0 C++11 the default constructor was explicit made implicit

    See also

    		 gets or sets the contents of underlying string device object
    (public member function) [edit]
    		constructs a basic_stringbuf object
    (public member function of std::basic_stringbuf<CharT,Traits,Allocator>) [edit]