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

 

C++

Compiler support

Freestanding and hosted

Language

Standard library

Standard library headers

Named requirements

Feature test macros(C++20)

Language support library

Concepts library(C++20)

Diagnostics library

Memory management library

Metaprogramming library(C++11)

General utilities library

Containers library

Iterators library

Ranges library(C++20)

Algorithms library

Strings library

Text processing library

Numerics library

Date and time library

Input/output library

Filesystem library(C++17)

Concurrency support library(C++11)

Execution control library(C++26)

Technical specifications

Symbols index

External libraries

 

Input/output library

I/O manipulators

Print functions(C++23)

C-style I/O

Buffers

basic_streambuf

basic_filebuf

basic_stringbuf

basic_spanbuf (C++23)

strstreambuf (C++98/26*)

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

basic_ispanstream (C++23)

basic_ospanstream (C++23)

basic_spanstream (C++23)

istrstream (C++98/26*)

ostrstream (C++98/26*)

strstream (C++98/26*)

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_flushnoemit_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 positioning of the fill characters in an output stream. left and right apply to any type being 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).

The initial default for standard streams is equivalent to right.

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

Output:

Default positioning: *******-1.23 ********0x2a ***USD *1.23   Left positioning: -1.23******* 0x2a******** USD *1.23***   Internal positioning: -*******1.23 0x********2a USD ****1.23   Right positioning: *******-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)
showbasenoshowbase	controls whether prefix is used to indicate numeric base (function)