std::left, std::right, std::internal

 

C++

Language

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)

 

Input/output library

I/O manipulators

C-style I/O

Buffers

basic_streambuf

basic_filebuf

basic_stringbuf

strstreambuf (deprecated)

Streams

Abstractions

ios_base

basic_ios

basic_istream

basic_ostream

basic_iostream

File I/O

basic_ifstream

basic_ofstream

basic_fstream

String I/O

basic_istringstream

basic_ostringstream

basic_stringstream

Array I/O

istrstream (deprecated)

ostrstream (deprecated)

strstream (deprecated)

Types

streamoff

streamsize

fpos

Error category interface

iostream_category (C++11)

io_errc (C++11)

 

Input/output manipulators

Floating-point formatting
showpoint noshowpoint setprecision	fixed scientific hexfloat defaultfloat (C++11) (C++11)
Integer formatting
setbase showbase noshowbase	dec hex oct
Boolean formatting
boolalpha noboolalpha
Field width and fill control
setfill setw	internal left right
Other formatting
showpos noshowpos	uppercase nouppercase
Whitespace processing
ws ends	skipws noskipws
Output flushing
flush endl	unitbuf nounitbuf
Status flags manipulation
resetiosflags	setiosflags
Time and money I/O
get_money (C++11) get_time (C++11)	put_money (C++11) put_time (C++11)

 

Defined in header <ios>
std::ios_base& left( std::ios_base& str );	(1)
std::ios_base& right( std::ios_base& str );	(2)
std::ios_base& internal( std::ios_base& str );	(3)

Modifies the default positioning of the fill characters. left and right apply to any output, internal applies to integer, floating-point, and monetary output. Has no effect on input.

1) sets the adjustfield of the stream str to left as if by calling str.setf(std::ios_base::left, std::ios_base::adjustfield)

2) sets the adjustfield of the stream str to right as if by calling str.setf(std::ios_base::right, std::ios_base::adjustfield)

3) sets the adjustfield of the stream str to internal as if by calling str.setf(std::ios_base::internal, std::ios_base::adjustfield)

This is an I/O manipulator, it may be called with an expression such as out << std::left for any out of type std::basic_ostream or with an expression such as in >> std::left for any in of type std::basic_istream.

Parameters

str

-

reference to I/O stream

Return value

str (reference to the stream after manipulation)

Example

#include <iostream>
#include <iomanip>
#include <locale>
int main()
{
    std::cout.imbue(std::locale("en_US.utf8"));
    std::cout << "Left fill:\n" << std::left << std::setfill('*')
              << std::setw(12) << -1.23  << '\n'
              << std::setw(12) << std::hex << std::showbase << 42 << '\n'
              << std::setw(12) << std::put_money(123, true) << "\n\n";
 
    std::cout << "Internal fill:\n" << std::internal
              << std::setw(12) << -1.23  << '\n'
              << std::setw(12) << 42 << '\n'
              << std::setw(12) << std::put_money(123, true) << "\n\n";
 
    std::cout << "Right fill:\n" << std::right
              << std::setw(12) << -1.23  << '\n'
              << std::setw(12) << 42 << '\n'
              << std::setw(12) << std::put_money(123, true) << '\n';
}

Output:

Left fill:
-1.23*******
0x2a********
USD *1.23***
 
Internal fill:
-*******1.23
0x********2a
USD ****1.23
 
Right fill:
*******-1.23
********0x2a
***USD *1.23

See also

setw	changes the width of the next input/output field (function)
setfill	changes the fill character (function template)