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  1. #include <iostream>
  2.  
  3. class space_delimited_output_buffer : public std::streambuf
  4. {
  5. public:
  6.     space_delimited_output_buffer(std::streambuf* sbuf)
  7.         : m_sbuf(sbuf)
  8.     { }
  9.  
  10.     virtual int_type overflow(int_type c)
  11.     {
  12.         return m_sbuf->sputc(c);
  13.     }
  14.  
  15.     virtual int sync()
  16.     {
  17.         if (ok_to_write)
  18.             this->sputc(' ');
  19.         else
  20.             ok_to_write = true;
  21.  
  22.         return internal_sync();
  23.     }
  24. private:
  25.     std::streambuf* m_sbuf;
  26.     bool ok_to_write = false;
  27.  
  28.     int internal_sync()
  29.     {
  30.         return m_sbuf->pubsync();
  31.     }
  32. };
  33.  
  34. class space_delimited_output_stream
  35.     : public std::ostream
  36.     , private virtual space_delimited_output_buffer
  37. {
  38. public:
  39.     space_delimited_output_stream(std::ostream& os)
  40.         : std::ostream(this)
  41.         , space_delimited_output_buffer(os.rdbuf())
  42.     {
  43.         this->tie(this); 
  44.     }
  45. };
  46.  
  47. int main() {
  48.     space_delimited_output_stream os(std::cout);
  49.     os << "abc" << 123 << "xyz";
  50. }
Success #stdin #stdout 0s 3300KB
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stdin
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Standard input is empty
stdout
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abc 123 xyz
https://ideone.com/D3LVfF
language:
C++14 (gcc 8.3)
created:
11 years ago
visibility:
public

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