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What moves the record indicator?

Posted on 2002-04-04
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Last Modified: 2010-04-02
I am a novice at C++ and am just learning the language and am getting into files, hence my question.  

When reading a file, what moves the record indicator to the next record?  I have been introduced to structs, but this question is before structs.

Thanks.
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Question by:cccgsmith
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bluprint earned 400 total points
ID: 6919002
It depends on how you read the file. Generally speaking, when a file is opened, there is a pointer that points to the beginning of the file.

If a particular function or operator will "read a line", it reads until it finds a "newline" character, it then moves the pointer to the character after the newline character (which is the beginning of the next line).

In some cases, there are functions which will read one character at a time, instead of a line at a time. In this case, the pointer moves along one character at a time, and the function returns after reading one character.

So, to be sure and answer your question:
"what moves the record indicator to the next record", the answer is:

Since the entire file is stored (on the HD) in such a way that there is really no such thing as "the next record" in the file (there is only a series of bytes, without much meaning), there is only an indicator (newline character) that tells where the current line ends, and the next begins. This indicator is then used by editors, programming languages, etc. to provide a common indicator as to what constitutes a new line.

By the way, the particular character used to indicate a newline varies depending on OS. For Unix based systems, it's typically the value 0A in hex, which is a newline or line-feed character (both names are used).

For Windows however, there a two-character sequence is used to signify a newline, 0A0D, which is line-feed followed by a carriage return.


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by:cccgsmith
ID: 6919087
Good answer.  Since the newline character is invisible, I forgot about it, hence my problem in comprehending what was taking place.

Thanks.
 
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