std::streamsize

 

C++

Compiler support

Freestanding and hosted

Language

Standard library

Standard library headers

Named requirements

Feature test macros (C++20)

Language support library

Concepts library (C++20)

Metaprogramming library (C++11)

Diagnostics library

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Filesystem library (C++17)

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Technical specifications

Symbols index

External libraries

 

Input/output library

I/O manipulators

Print functions (C++23)

C-style I/O

Buffers

basic_streambuf

basic_filebuf

basic_stringbuf

basic_spanbuf (C++23)

strstreambuf (C++98/26*)

basic_syncbuf (C++20)

Streams

Abstractions

ios_base

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basic_istream

basic_ostream

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File I/O

basic_ifstream

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basic_fstream

String I/O

basic_istringstream

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basic_stringstream

Array I/O

basic_ispanstream (C++23)

basic_ospanstream (C++23)

basic_spanstream (C++23)

istrstream (C++98/26*)

ostrstream (C++98/26*)

strstream (C++98/26*)

Synchronized Output

basic_osyncstream (C++20)

Types

streamoff

streamsize

fpos

Error category interface

iostream_category (C++11)

io_errc (C++11)

 

Defined in header <ios>
typedef /*implementation-defined*/ streamsize;

The type std::streamsize is a signed integral type used to represent the number of characters transferred in an I/O operation or the size of an I/O buffer. It is used as a signed counterpart of std::size_t, similar to the POSIX type ssize_t.

Notes

Except in the constructors of std::strstreambuf, negative values of std::streamsize are never used.

Example

Run this code

#include <iostream>
#include <type_traits>
 
static_assert(std::is_signed_v<std::streamsize>);
 
int main()
{
    std::cout << sizeof(std::streamsize) << '\n';
}

Possible output:

8

See also

gcount	returns number of characters extracted by last unformatted input operation (public member function of std::basic_istream<CharT,Traits>)
ignore	extracts and discards characters until the given character is found (public member function of std::basic_istream<CharT,Traits>)
read	extracts blocks of characters (public member function of std::basic_istream<CharT,Traits>)
write	inserts blocks of characters (public member function of std::basic_ostream<CharT,Traits>)