std::showbase, std::noshowbase

 

C++

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Regular expressions library (C++11)

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Input/output library

I/O manipulators

C-style I/O

Buffers

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ios_base

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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& showbase( std::ios_base& str );	(1)
std::ios_base& noshowbase( std::ios_base& str );	(2)

1) enables the showbase flag in the stream str as if by calling str.setf(std::ios_base::showbase)

2) disables the showbase flag in the stream str as if by calling str.unsetf(std::ios_base::showbase)

This is an I/O manipulator, it may be called with an expression such as out << std::showbase for any out of type std::basic_ostream or with an expression such as in >> std::showbase 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 <sstream>
#include <locale>
#include <iostream>
#include <iomanip>
int main()
{
    // showbase affects the output of octals and hexadecimals
    std::cout << std::hex
              << "showbase: " << std::showbase << 42 << '\n'
              << "noshowbase: " << std::noshowbase << 42 << '\n';
 
    // and both input and output of monetary values
    std::locale::global(std::locale("en_US.utf8"));
    long double val = 0;
    std::istringstream is("3.14");
    is >> std::showbase >> std::get_money(val);
    std::cout << "With showbase, parsing 3.14 as money gives " << val << '\n';
    is.seekg(0);
    is >> std::noshowbase >> std::get_money(val);
    std::cout << "Without showbase, parsing 3.14 as money gives " << val << '\n';
}

Output:

showbase: 0x2a
noshowbase: 2a
With showbase, parsing 3.14 as money gives 0
Without showbase, parsing 3.14 as money gives 314

See also

resetiosflags	clears the specified ios_base flags (function)
setiosflags	sets the specified ios_base flags (function)