mrquija
asked on
Copying a files contents
I need to delete a row from a file with many rows in it. Does anyone have any suggestions as to THE MOST EFFICIENT/FASTEST algorithm KNOWN TO MANKIND on how to do this? I have some ideas, such as simply string copying from one file to the other and omitting the row that I dont want...but I dont know if that's THE FASTEST in the entire UNIVERSE. You know, they should make a search engine on this experts-exchange forum, I'm sure this question has been asked before, but I'm way too lazy to go through 2000 paq to perhaps find the one I need. Thanks to all.
ASKER
not sure what you mean by your comment of Asking mirkwood.
ASKER
by the way, I'm not asking for code...merely just suggestions/practical ideas for fastest completion of this task.
I can't tell you about the fastest method in the Universe. What you sketched seems ok.
You could add some info at the beginning of a record, like wether the record is in use or free (deleted) and the size of the record (not needed for fixed lenght). Once in a while you clean up the file by copying only used records into a new file.
You could add some info at the beginning of a record, like wether the record is in use or free (deleted) and the size of the record (not needed for fixed lenght). Once in a while you clean up the file by copying only used records into a new file.
Use memory mapped files
Since you're not asking for code...
Yes, copy line by line -- omiting the line you don't want.
Another techniqe would be to mark the first character with an ID you know means "don't use this line" -- such as changing
This is neat
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£his is neat
Yes, copy line by line -- omiting the line you don't want.
Another techniqe would be to mark the first character with an ID you know means "don't use this line" -- such as changing
This is neat
to
£his is neat
That was put in as comment Triskelion.
actually that depands on ur file structure !!! if its a sequential file then this is the approach .. in case u are the creator of the file .. then u can make this even faster ..
how about storing Linked List in a file with the pointer as file offset ..
regards
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