basic_streambuf::pbackfail
A protected virtual member function that tries to put back an element into the input stream, then make it the current element (pointed to by the next pointer).
virtual int_type pbackfail(
int_type _Meta = traits_type::eof( )
);
Parameters
- _Meta
The character to insert into the buffer, or traits_type::eof.
Return Value
If the function cannot succeed, it returns traits_type::eof or throws an exception. Otherwise, it returns some other value. The default behavior is to return traits_type::eof.
Remarks
If _Meta compares equal to traits_type::eof, the element to push back is effectively the one already in the stream before the current element. Otherwise, that element is replaced by traits_type::to_char_type(_Meta). The function can put back an element in various ways:
If a putback position is available, it can store the element into the putback position and decrement the next pointer for the input buffer.
It can make a putback position available by allocating new or additional storage for the input buffer.
For a stream buffer with common input and output streams, it can make a putback position available by writing out, to some external destination, some or all of the elements between the beginning and next pointers for the output buffer.
Requirements
Header: <streambuf>
Namespace: std