Pre-defined stream
Controls output to a stream buffer associated with the object stdout declared in <cstdio>.
None
#include <iostream> extern wostream wcout; 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.
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( ) |
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. 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 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 | Flush the output buffer. |
precision() 6 width() 0 fill() the space character flags() skipws | dec getloc() locale::locale()
// // 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; } }
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 synchronized.
If your compiler does not support namespaces, then you do not need the using declaration for std.
basic_ostream(3C++), iostream(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 27.3.2
ANSI X3J16/ISO WG21 Joint C++ Committee