std::basic_ostream<CharT,Traits>::write

basic_ostream& write( const char_type* s, std::streamsize count );

Behaves as an UnformattedOutputFunction. After constructing and checking the sentry object, outputs the characters from successive locations in the character array whose first element is pointed to by s. Characters are inserted into the output sequence until one of the following occurs:

exactly count characters are inserted
inserting into the output sequence fails (in which case setstate(badbit) is called)

Parameters

s	-	pointer to the character string to write
count	-	number of characters to write

Return value

*this

Exceptions

failure if an error occurred (the error state flag is not goodbit) and exceptions() is set to throw for that state.

If an internal operation throws an exception, it is caught and badbit is set. If exceptions() is set for badbit, the exception is rethrown.

Notes

This function is not overloaded for the types signed char or unsigned char, unlike the formatted operator<<

Also, unlike the formatted output functions, this function does not set the failbit on failure.

When using a non-converting locale (the default locale is non-converting), the overrider of this function in std::basic_ofstream may be optimized for zero-copy bulk I/O (by means of overriding std::streambuf::xsputn)

Example

This function may be used to output object representations, i.e. binary output

Run this code

#include <iostream>
 
int main()
{
    int n = 0x41424344;
    std::cout.write(reinterpret_cast<char*>(&n), sizeof n) << '\n';
 
    char c[]="This is sample text.";
    std::cout.write(c,4)<<'\n';
}

Possible output:

DCBA
This

Language
Standard Library Headers
Freestanding and hosted implementations
Named requirements
Language support library
Concepts library (C++20)
Diagnostics library
Utilities library
Strings library
Containers library
Iterators library
Ranges library (C++20)
Algorithms library
Numerics library
Input/output library
Localizations library
Regular expressions library (C++11)
Atomic operations library (C++11)
Thread support library (C++11)
Filesystem library (C++17)
Technical Specifications

I/O manipulators
C-style I/O
Buffers
basic_streambuf
basic_filebuf
basic_stringbuf
strstreambuf (deprecated in C++98)
basic_syncbuf (C++20)
Streams
Abstractions
ios_base
basic_ios
basic_istream
basic_ostream
basic_iostream
File I/O
basic_ifstream
basic_ofstream
basic_fstream
String I/O
basic_istringstream
basic_ostringstream
basic_stringstream
Array I/O
istrstream (deprecated in C++98)
ostrstream (deprecated in C++98)
strstream (deprecated in C++98)
Synchronized Output
basic_osyncstream (C++20)
Types
streamoff
streamsize
fpos
Error category interface
iostream_category (C++11)
io_errc (C++11)