output-stream-manipulators-with-one-argument-int-or-long.md

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Learn more about: Output Stream Manipulators with One Argument (int or long)	Output Stream Manipulators with One Argument (int or long)	11/04/2016	output streams, int or long argument manipulators	338f3164-b5e2-4c5a-a605-7d9dc3629ca1

Output Stream Manipulators with One Argument (int or long)

The iostream class library provides a set of macros for creating parameterized manipulators. Manipulators with a single int or long argument are a special case. To create an output stream manipulator that accepts a single int or long argument (like setw), you must use the _Smanip macro, which is defined in <iomanip>. This example defines a fillblank manipulator that inserts a specified number of blanks into the stream:

Example

// output_stream_manip.cpp
// compile with: /GR /EHsc
#include <iostream>
#include <iomanip>
using namespace std;

void fb( ios_base& os, int l )
{
   ostream *pos = dynamic_cast<ostream*>(&os);
   if (pos)
   {
      for( int i=0; i < l; i++ )
      (*pos) << ' ';
   };
}

_Smanip<int>
   __cdecl fillblank(int no)
   {
   return (_Smanip<int>(&fb, no));
   }

int main( )
{
   cout << "10 blanks follow" << fillblank( 10 ) << ".\n";
}

See also

Custom Manipulators with Arguments