std::basic_istream<CharT,Traits>:: get

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C++
Input/output library
std::basic_istream
int_type get ( ) ;
(1)
basic_istream & get ( char_type & ch ) ;
(2)
basic_istream & get ( char_type * s, std:: streamsize count ) ;
(3)
basic_istream & get ( char_type * s, std:: streamsize count, char_type delim ) ;
(4)
basic_istream & get ( basic_streambuf & strbuf ) ;
(5)
basic_istream & get ( basic_streambuf & strbuf, char_type delim ) ;
(6)

Extracts character or characters from stream.

All versions behave as UnformattedInputFunction s . After constructing and checking the sentry object, these functions perform the following:

1) Reads one character and returns it if available. Otherwise, returns Traits :: eof ( ) and sets failbit and eofbit .
2) Reads one character and stores it to ch if available. Otherwise, leaves ch unmodified and sets failbit and eofbit . Note that this function is not overloaded on the types signed char and unsigned char , unlike the formatted character input operator>>.
3) Same as get ( s, count, widen ( ' \n ' ) ) , that is, reads at most std:: max ( 0 , count - 1 ) characters and stores them into character string pointed to by s until ' \n ' is found.
4) Reads characters and stores them into the successive locations of the character array whose first element is pointed to by s . Characters are extracted and stored until any of the following occurs:
  • count is less than 1 or count - 1 characters have been stored.
  • end of file condition occurs in the input sequence ( setstate ( eofbit ) is called).
  • the next available input character c equals delim , as determined by Traits :: eq ( c, delim ) . This character is not extracted (unlike getline() ).
In any case, if count > 0 , a null character ( CharT ( ) is stored in the next successive location of the array.
5) Same as get ( strbuf, widen ( ' \n ' ) ) , that is, reads available characters and inserts them to the given basic_streambuf object until ' \n ' is found.
6) Reads characters and inserts them to the output sequence controlled by the given basic_streambuf object. Characters are extracted and inserted into strbuf until any of the following occurs:
  • end of file condition occurs in the input sequence.
  • inserting into the output sequence fails (in which case the character that could not be inserted, is not extracted).
  • the next available input character c equals delim , as determined by Traits :: eq ( c, delim ) . This character is not extracted.
  • an exception occurs (in which case the exception is caught and not rethrown).

If no characters were extracted, calls setstate ( failbit ) .

All versions set the value of gcount() to the number of characters extracted.

Parameters

ch - reference to the character to write the result to
s - pointer to the character string to store the characters to
count - size of character string pointed to by s
delim - delimiting character to stop the extraction at. It is not extracted and not stored
strbuf - stream buffer to read the content to

Return value

1) The extracted character or Traits :: eof ( ) .
2-6) * 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.

Example

Run this code 
#include <iostream>
#include <sstream>
 
int main()
{
    std::istringstream s1("Hello, world.");
    char c1 = s1.get(); // reads 'H'
    std::cout << "after reading " << c1 << ", gcount() == " <<  s1.gcount() << '\n';
 
    char c2;
    s1.get(c2);         // reads 'e'
    char str[5];
    s1.get(str, 5);     // reads "llo,"
    std::cout << "after reading " << str << ", gcount() == " <<  s1.gcount() << '\n';
 
    std::cout << c1 << c2 << str;
    s1.get(*std::cout.rdbuf()); // reads the rest, not including '\n'
    std::cout << "\nAfter the last get(), gcount() == " << s1.gcount() << '\n';
}

Output: 

after reading H, gcount() == 1
after reading llo,, gcount() == 4
Hello, world.
After the last get(), gcount() == 7

Defect reports

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

DR Applied to Behavior as published Correct behavior
LWG 370 C++98 the effect of overload (5) was get ( s, count, widen ( ' \n ' ) ) ,
which is the effect of overload (3) 		corrected to
get ( strbuf, widen ( ' \n ' ) )
LWG 531 C++98 overloads (3,4) could not handle the
case where count is non-positive 		no character is
extracted in this case

See also

extracts blocks of characters
(public member function)
extracts formatted data
(public member function)
extracts characters and character arrays
(function template)
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