Return the character at the current input position, if a character is available, and traits_type::eof() otherwise. Update the end of the input area, egptr, if additional characters are available (as may occur if additional characters have been written to the string buffer). Note that this operation is similar to uflow, but does not advance the current input position.
Declared in <bslstl_stringbuf.h>
virtual
basic_stringbuf<CHAR_TYPE, CHAR_TRAITS, ALLOCATOR>::int_type
underflow();