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  1. #include <iostream>
  2.  
  3. class keep_last_char_outbuf : public std::streambuf {
  4. public:
  5.     keep_last_char_outbuf(std::streambuf* buf) : buf(buf), last_char(traits_type::eof()) {
  6.         // no buffering, overflow on every char
  7.         setp(0, 0);
  8.     }
  9.     char get_last_char() const { return last_char; }
  10.  
  11.     virtual int_type overflow(int_type c) {
  12.         buf->sputc(c);
  13.         last_char = c;
  14.         return c;
  15.     }
  16. private:
  17.     std::streambuf* buf;
  18.     char last_char;
  19. };
  20.  
  21. int main() {
  22.    std::streambuf* cbuf = std::cout.rdbuf();
  23.    std::cout.flush();
  24.    keep_last_char_outbuf keep_last_buf(cbuf);
  25.    std::cout.rdbuf(&keep_last_buf);
  26.  
  27.    std::cout << "ala ma kota\n";
  28.  
  29.    char last_char = keep_last_buf.get_last_char();
  30.    if (last_char == '\r' || last_char == '\n')
  31.       std::cout << "\nLast char was newline: " << int(last_char) << "\n";
  32.    else
  33.       std::cout << "\nLast char: '" << last_char << "'\n";
  34.  
  35.    std::cout << "ala ma kota";
  36.    last_char = keep_last_buf.get_last_char();
  37.    if (last_char == '\r' || last_char == '\n')
  38.       std::cout << "\nLast char was newline: " << int(last_char) << "\n";
  39.    else
  40.       std::cout << "\nLast char: '" << last_char << "'\n";
  41.  
  42.    std::cout.rdbuf(cbuf);
  43. }
Success #stdin #stdout 0.01s 2684KB
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stdin
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ala ma kota
stdout
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ala ma kota

Last char was newline: 10
ala ma kota
Last char: 'a'
https://ideone.com/HbQ2r
language:
C++ (gcc 8.3)
created:
11 years ago
visibility:
secret

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