std::setfill

 

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)

Metaprogramming library (C++11)

Diagnostics library

General utilities library

Strings library

Containers library

Iterators library

Ranges library (C++20)

Algorithms library

Numerics library

Localizations library

Input/output library

Filesystem library (C++17)

Regular expressions library (C++11)

Concurrency support library (C++11)

Execution support 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 <iomanip>
template< class CharT > /*unspecified*/ setfill( CharT c );

When used in an expression out << setfill(c) sets the fill character of the stream out to c.

Parameters

c

-

new value for the fill character

Return value

An object of unspecified type such that

• if out is an object of type std::basic_ostream<CharT, Traits>, the expression out << setfill(c)
  • has type std::basic_ostream<CharT, Traits>&
  • has value out
  • behaves as if it called f(out, c)

where the function f is defined as:

template<class CharT, class Traits>
void f(std::basic_ios<CharT, Traits>& str, CharT c)
{
    // set fill character
    str.fill(c);
}

Notes

The current fill character may be obtained with std::ostream::fill.

Example

Run this code

#include <iomanip>
#include <iostream>
 
int main()
{
    std::cout << "default fill: [" << std::setw(10) << 42 << "]\n"
              << "setfill('*'): [" << std::setfill('*')
                                   << std::setw(10) << 42 << "]\n";
}

Output:

default fill: [        42]
setfill('*'): [********42]

Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

DR	Applied to	Behavior as published	Correct behavior
LWG 183	C++98	setbase could only be used with streams of type std::ostream	usable with any output character stream

See also

fill	manages the fill character (public member function of std::basic_ios<CharT,Traits>)
internalleftright	sets the placement of fill characters (function)
setw	changes the width of the next input/output field (function)