fork download
copy 
  1. #include <iostream>
  2. #include <iomanip>
  3.  
  4. /** provides a helper class to work with streams.
  5.  *
  6.  * It stores current format states of a stream in constructor and
  7.  * recovers these settings in destructor.
  8.  *
  9.  * Example:
  10.  * <pre>
  11.  * { // backup states of std::cout
  12.  *   IOSFmtBackup stateCOut(std::cout);
  13.  *   // do some formatted output
  14.  *   std::cout
  15.  *     << "dec: " << std::dec << 123 << std::endl
  16.  *     << "hex: " << std::hex << std::setw(8) << std::setfill('0')
  17.  *     << 0xdeadbeef << std::endl;
  18.  * } // destruction of stateCOut recovers former states of std::cout
  19.  * </pre>
  20.  */
  21. class IOSFmtBackup {
  22.  
  23.   // variables:
  24.   private:
  25.     /// the concerning stream
  26.     std::ios &_stream;
  27.     /// the backup of formatter states
  28.     std::ios _fmt;
  29.  
  30.   // methods:
  31.   public:
  32.     /// @name Construction & Destruction
  33.     //@{
  34.  
  35.     /** constructor.
  36.      *
  37.      * @param stream the stream for backup
  38.      */
  39.     explicit IOSFmtBackup(std::ios &stream):
  40.       _stream(stream), _fmt(0)
  41.     {
  42.       _fmt.copyfmt(_stream);
  43.     }
  44.  
  45.     /// destructor.
  46.     ~IOSFmtBackup() { _stream.copyfmt(_fmt); }
  47.  
  48.     // disabled:
  49.     IOSFmtBackup(const IOSFmtBackup&) = delete;
  50.     IOSFmtBackup& operator=(const IOSFmtBackup&) = delete;
  51.     //@}
  52. };
  53.  
  54. int main()
  55. {
  56.   { // backup states of std::cout
  57.     IOSFmtBackup stateCOut(std::cout);
  58.     // do some formatted output
  59.     std::cout
  60.       << "dec: " << std::dec << 123 << std::endl
  61.       << "hex: " << std::hex << std::setw(8) << std::setfill('0')
  62.       << 0xdeadbeef << std::endl
  63.       << "123 in current: " << 123 << std::endl;
  64.   } // destruction of stateCOut recovers former states of std::cout
  65.   // check whether formatting is recovered
  66.   std::cout << "123 after recovered: " << 123 << std::endl;
  67.   return 0;
  68. }
Success #stdin #stdout 0s 4452KB
comments (?)
stdin
copy 
Standard input is empty
stdout
copy 
dec: 123
hex: deadbeef
123 in current: 7b
123 after recovered: 123
https://ideone.com/zJNoTE
language:
C++ (gcc 8.3)
created:
7 years ago
visibility:
public

Share or Embed source code

Discover > Sphere Engine API

The brand new service which powers Ideone!

Discover > IDE Widget

Widget for compiling and running the source code in a web browser!