C++程序  |  31行  |  657 B

//===----------------------------------------------------------------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is dual licensed under the MIT and the University of Illinois Open
// Source Licenses. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//

// <streambuf>

// template <class charT, class traits = char_traits<charT> >
// class basic_streambuf;

// int_type underflow();

#include <streambuf>
#include <cassert>

struct test
    : public std::basic_streambuf<char>
{
    test() {}
};

int main()
{
    test t;
    assert(t.sgetc() == -1);
}