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std::basic_...buf::sungetc(3) C++ Standard Libarystd::basic_...buf::sungetc(3) NAME std::basic_streambuf::sungetc - std::basic_streambuf::sungetc Synopsis int_type sungetc(); If a putback position is available in the get area (gptr() > eback()), then decrements the next pointer (gptr()) and returns the character it now points to. If a putback position is not available, then calls pbackfail() to back up the input sequence if possible. The I/O stream function basic_istream::unget is implemented in terms of this function. Parameters (none) Return value If putback position was available, returns the character that the next pointer is now pointing at, converted to int_type with Traits::to_int_type(*gptr()). The next single-character input from this streambuf will return this charac- ter. If putback position was not available, returns what pbackfail() re- turns, which is Traits::eof() on failure. Example // Run this code #include <iostream> #include <sstream> int main() { std::stringstream s("abcdef"); // gptr() points to 'a' char c1 = s.get(); // c = 'a', gptr() now points to 'b' char c2 = s.rdbuf()->sungetc(); // same as s.unget(): gptr() points to 'a' again char c3 = s.get(); // c3 = 'a', gptr() now points to 'b' char c4 = s.get(); // c4 = 'b', gptr() now points to 'c' std::cout << c1 << c2 << c3 << c4 << '\n'; s.rdbuf()->sungetc(); // back to 'b' s.rdbuf()->sungetc(); // back to 'a' int eof = s.rdbuf()->sungetc(); // nothing to unget: pbackfail() fails if (eof == EOF) std::cout << "Nothing to unget after 'a'\n"; } Output: aaab Nothing to unget after 'a' See also sputbackc puts one character back in the input sequence (public member function) unget unextracts a character (public member function of std::ba- sic_istream<CharT,Traits>) http://cppreference.com 2022.07.31 std::basic_...buf::sungetc(3)
NAME | Synopsis | Parameters | Return value | Example | Output: | See also
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