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

C++

Language

Headers

Freestanding and hosted implementations

Named requirements

Language support library

Concepts library (C++20)

Diagnostics library

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)

Filesystem library (C++17)

Technical Specifications

Input/output library

I/O manipulators

C-style I/O

Buffers

basic_streambuf

basic_filebuf

basic_stringbuf

strstreambuf (deprecated)

basic_syncbuf (C++20)

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)

Synchronized Output

basic_osyncstream (C++20)

Types

streamoff

streamsize

fpos

Error category interface

iostream_category (C++11)

io_errc (C++11)

Input/output manipulators

Floating-point formatting
showpointnoshowpoint setprecision	fixedscientifichexfloatdefaultfloat (C++11)(C++11)
Integer formatting
setbase showbasenoshowbase	dechexoct
Boolean formatting
boolalphanoboolalpha
Field width and fill control
setfill setw	internalleftright
Other formatting
showposnoshowpos	uppercasenouppercase
Whitespace processing
ws ends	skipwsnoskipws
Output flushing
flush endl flush_emit (C++20)	unitbufnounitbuf emit_on_flushno_emit_on_flush (C++20)(C++20)
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)
Quoted manipulator
quoted (C++14)

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

Run this code

#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)