std::basic_istream::read

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basic_istream& read( char_type* s, std::streamsize count );

Extracts characters from stream.

Behaves as UnformattedInputFunction. After constructing and checking the sentry object, extracts characters and stores them into successive locations of the character array whose first element is pointed to by s. Characters are extracted and stored until any of the following conditions occurs:

count characters were extracted and stored

end of file condition occurs on the input sequence (in which case, setstate(failbit|eofbit) is called.

#include <iostream>
#include <string>
#include <sstream>
#include <cstdint>
 
int main()
{
    std::string bin = {'\x12', '\x12', '\x12', '\x12'};
    std::istringstream raw(bin);
    std::uint32_t n;
    raw.read(reinterpret_cast<char*>(&n), sizeof n);
    std::cout << std::hex << std::showbase << n << '\n';
}

Output:

0x12121212

[edit] See also


write	inserts blocks of characters (public member function of `std::basic_ostream`)

operator>>	extracts formatted data (public member function)

readsome	extracts already available blocks of characters (public member function)

get	extracts characters (public member function)

getline	extracts characters until the given character is found (public member function)

fread	reads from a file (function)

Language
Standard library headers
Concepts
Utilities library
Strings library
Containers library
Algorithms library
Iterators library
Numerics library
Input/output library
Localizations library
Regular expressions library (C++11)
Atomic operations library (C++11)
Thread support library (C++11)

std::basic_istream::read

Contents

[edit] Parameters

[edit] Return value

[edit] Example

[edit] See also

s	-	pointer to the character array to store the characters to
count	-	number of characters to read