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wcout



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wcout


Pre-defined stream

Data Type and Member Function Indexes
(exclusive of constructors and destructors)

None

Synopsis

#include <iostream>
extern wostream wcout;

Description

wostream wcout;

    The object wcout controls output to a stream buffer associated with the object stdout declared in <cstdio>. By default the standard C and C++ streams are synchronized, but performance can be improved by using the ios_base member function synch_with_stdio to desynchronize them.

    After the object wcin is initialized, wcin.tie() returns &wcout, which implies that wcin and wcout are synchronized. wcout uses the locale codecvt facet to convert the wide characters it receives to the tiny characters it outputs to stdout.

Formatting

The formatting is done through member functions or manipulators.

Manipulators
Member Functions
showpos
setf(ios_base::showpos)
noshowpos
unsetf(ios_base::showpos)
showbase
setf(ios_base::showbase)
noshowbase
unsetf(ios_base::showbase)
uppercase
setf(ios_base::uppercase)
nouppercase
unsetf(ios_base::uppercase)
showpoint
setf(ios_base::showpoint)
noshowpoint
unsetf(ios_base::showpoint)
boolalpha
setf(ios_base::boolalpha)
noboolalpha
unsetf(ios_base::boolalpha)
unitbuf
setf(ios_base::unitbuf)
nounitbuf
unsetf(ios_base::unitbuf)
internal
setf(ios_base::internal,
ios_base::adjustfield)
left
setf(ios_base::left,
ios_base::adjustfield)
right
setf(ios_base::right,
ios_base::adjustfield)
dec
setf(ios_base::dec,
ios_base::basefield)
hex
setf(ios_base::hex,
ios_base::basefield)
oct
setf(ios_base::oct,
ios_base::basefield)
fixed
setf(ios_base::fixed,
ios_base::floatfield)
scientific
setf(ios_base::scientific,
ios_base::floatfield)
resetiosflags
(ios_base::fmtflags flag)
setf(0,flag)
setiosflags
(ios_base::fmtflags flag)
setf(flag)
setbase(int base)
see above
setfill(char_type c)
fill(c)
setprecision(int n)
precision(n)
setw(int n)
width(n)
endl
 
ends
 
flush
flush( )

Description

showpos
Generates a + sign in non-negative generated numeric output.
showbase
Generates a prefix indicating the numeric base of generated integer output.
uppercase
Replaces certain lowercase letters with their uppercase equivalents in generated output.
showpoint
Generates a decimal-point character unconditionally in generated floating-point output.
boolalpha
Inserts and extracts bool type in alphabetic format.
unitbuf
Flushes output after each output operation.
internal
Adds fill characters at a designated internal point in certain generated output, or identical to right if no such point is designated.
left
Adds fill characters on the right (final positions) of certain generated output.
right
Adds fill characters on the left (initial positions) of certain generated output.
dec
Converts integer input or generates integer output in decimal base.
hex
Converts integer input or generates integer output in hexadecimal base.
oct
Converts integer input or generates integer output in octal base.
fixed
Generates floating-point output in fixed-point notation.
scientific
Generates floating-point output in scientific notation.
resetiosflagss
 
(ios_base::fmtflags flag)
Resets the fmtflags field flag
setiosflags
 
(ios_base::fmtflags flag)
Sets up the flag flag
setbase(int base)
Converts integer input or generates integer output in base base. The parameter base can be 8, 10 or 16.
setfill(char_type c)
Sets the character used to pad (fill) an output conversion to the specified field width.
setprecision(int n)
Sets the precision (number of digits after the decimal point) to generate on certain output conversions.
setw(int n)
Sets the field with (number of characters) to generate on certain output conversions.
endl
Inserts a newline character into the output sequence and flush the output buffer.
ends
Inserts a null character into the output sequence.
flush
Flushes the output buffer.

Default Values

precision()            6
width()                0
fill()                 the space character
flags()                skipws | dec
getloc()               locale::locale()

Examples

//
// wcout example one
//
#include<iostream>
#include<iomanip>

void main ( )
{
  using namespace std; 

  int i;
  float f;
  
  // read an integer and a float from stdin
  cin >> i >> f;

  // output the integer and goes at the line
  wcout << i << endl;

  // output the float and goes at the line
  wcout << f << endl;   

  // output i in hexa
  wcout << hex << i << endl;

  // output i in octal and then in decimal
  wcout << oct << i << dec << i << endl;  

  // output i preceded by its sign
  wcout << showpos << i << endl;

  // output i in hexa
  wcout << setbase(16) << i << endl;

  // output i in dec and pad to the left with character
  // @ until a width of 20
  // if you input 45 it outputs 45@@@@@@@@@@@@@@@@@@ 
  wcout << setfill(L'@') << setw(20) << left << dec << i;
  wcout << endl;

  // output the same result as the code just above
  // but uses member functions rather than manipulators
  wcout.fill('@');
  wcout.width(20);
  wcout.setf(ios_base::left, ios_base::adjustfield);
  wcout.setf(ios_base::dec, ios_base::basefield);
  wcout << i << endl; 

  // outputs f in scientific notation with
  // a precision of 10 digits
  wcout << scientific << setprecision(10) << f << endl;

  // change the precision to 6 digits
  // equivalents to wcout << setprecision(6);
  wcout.precision(6);

  // output f and goes back to fixed notation
  wcout << f << fixed << endl;
  
}

//
// wcout example two
//
#include <iostream>

void main ( )
{
  using namespace std;

  wchar_t p[50];

  wcin.getline(p,50);

  wcout << p;   
}

//
// wcout example three
//
#include <iostream>
#include <fstream>

void main ( )
{
  using namespace std;  

  // open the file "file_name.txt"
  // for reading
  wifstream in("file_name.txt");
  
  // output the all file to stdout
  if ( in ) 
    wcout << in.rdbuf(); 
  else
    { 
      wcout << "Error while opening the file";  
      wcout << endl;
    }
}

Warnings

Keep in mind that the manipulator endl flushes the stream buffer. Therefore it is recommended to use L'\n' if your only intent is to go at the line. It will greatly improve performance when C and C++ streams are not synchronized.

See Also

basic_ostream(3C++), basic_filebuf(3C++), cin(3C++), cout(3C++), cerr(3C++), clog(3C++), wcin(3C++), wcerr(3C++), wclog(3C++), iomanip(3C++), ios_base(3C++), basic_ios(3C++)

Working Paper for Draft Proposed International Standard for Information Systems--Programming Language C++, Section 27.3.1

Standards Conformance

ANSI X3J16/ISO WG21 Joint C++ Committee


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