wcout(3C++) - wcout(3C++)
Standard C++ Library Copyright 1998, Rogue Wave Software, Inc.
NAMEwcout
- Controls output to a stream buffer associated with the object stdout
declared in <cstdio>.
SYNOPSIS
#include <iostream>
extern wostream wcout;
wostream wcout;
DESCRIPTION
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 gen‐
erated 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 cer‐
tain generated output. If no such point is designated, it's
identical to right.
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
resetiosflags
(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 con‐
versions
setw(int n) Sets the field with (number of characters) to generate on
certain output conversions
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 gen‐
erated 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 cer‐
tain generated output. If no such point is designated, it's
identical to right.
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
resetiosflags
(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 con‐
versions
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 Flush the output buffer.
DEFAULT VALUESprecision() 6
width() 0
fill() the space character
flags() skipws | dec
getloc()locale::locale()EXAMPLE
//
// wcout example #1
//
#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 #2
//
#include <iostream>
void main ( )
{
using namespace std;
wchar_t p[50];
wcin.getline(p,50);
wcout << p;
}
//
// wcout example #3
//
#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, use L`\n' if your only intent is to go at the line. It
greatly improves performance when C and C++ streams are not synchro‐
nized.
If your compiler does not support namespaces, then you do not need the
using declaration for std.
SEE ALSO
basic_ostream(3C++), basic_iostream(3C++), basic_filebuf(3C++),
cin(3C++), cout(3C++), cerr(3C++), clog(3C++), wcin(3C++), wcerr(3C++),
wclog(3C++), ios_base(3C++), basic_ios(3C++)
Working Paper for Draft Proposed International Standard for Information
Systems--Programming Language C++, Section 27.3.2
STANDARDS CONFORMANCE
ANSI X3J16/ISO WG21 Joint C++ Committee
Rogue Wave Software 02 Apr 1998 wcout(3C++)
