Is there a way we can decrement a file pointer. I searched online and I found the ungetc() function but what if we want to decrement the file pointer to point to the last string in the database? Also, how does ungetc put back a character?? Explain. Thanks in advance!!
anumash 0 Newbie Poster
Adak 419 Nearly a Posting Virtuoso
Check out fseek() to smartly maneuver around a file. Any time the records of the database are not fixed in their size, (that is, all the same size), you will find it more difficult finding your way around inside a file.
Conceptually, there is a tiny buffer, than can be used with ungetc(). Nothing is actually "put back" into the input stream, it's just put into the buffer, and a flag tells the next access to check that tiny buffer first. The actual implementation is left up to the compiler maker.
This is not a factual understanding, but my understanding of it. I'm sure you could Google and get better info.
deceptikon 1,790 Code Sniper Team Colleague Featured Poster
Check out fseek() to smartly maneuver around a file.
Note that arbitrary seeking on a stream opened in text mode is technically undefined. To use anything except an offset of 0 or the result of a previous ftell() call, the stream must be opened in binary mode.
Also, how does ungetc put back a character?? Explain.
If you're feeling adventurous enough to look at an actual implementation (it's written with clarity in mind), check out these links:
You'll see that a separate unget buffer is used to hold pushed back characters, where the buffer takes priority over the primary character buffer.
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