std::basic_istream<CharT,Traits>::peek (3) - Linux Manuals

std::basic_istream<CharT,Traits>::peek: std::basic_istream<CharT,Traits>::peek

NAME

std::basic_istream<CharT,Traits>::peek - std::basic_istream<CharT,Traits>::peek

Synopsis

int_type peek();

Behaves as UnformattedInputFunction. After constructing and testing the sentry object, reads the next character from the input stream without extracting it.

Parameters

(none)

Return value

If good() == true, returns the next character as obtained by rdbuf()->sgetc()
Otherwise, returns Traits::eof().

Exceptions

failure if an error occurred (the error state flag is not goodbit) and exceptions() is set to throw for that state.
If an internal operation throws an exception, it is caught and badbit is set. If exceptions() is set for badbit, the exception is rethrown.

Example

// Run this code

  #include <sstream>
  #include <iostream>
  int main()
  {
      std::istringstream s1("Hello, world.");
      char c1 = s1.peek();
      char c2 = s1.get();
      std::cout << "Peeked: " << c1 << " got: " << c2 << '\n';
  }

Output:

  Peeked: H got: H