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Deleting a record from a file

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PriyaJaiGanesh PriyaJaiGanesh is offline

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Deleting a record from a file

Dec 15th, 2004

hai!

(1)I have problem in deleting a record from a file.

I was told that the only way to delete a record from a file is to copy the file to another temporary file and then copy the records to the same file again by skipping the record that u need to delete i don't have problem until the copying of the file to the temporary file but i don't know how to skip the record that needs to be delete.

(2)what's the command to rename a file?

Plz anybody help me!

Urs,
PriyaJaiGanesh.

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duckman

Re: Deleting a record from a file

Dec 15th, 2004

read the old file, record for record.
Write all records to the tempfile, except the one(s) you want to delete.
Remove the old file.
Copy the tempfile completely to a new file with the same name as the old one.
Remove the tempfile.

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Posting Whiz in Training

Re: Deleting a record from a file

Dec 15th, 2004

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Originally Posted by PriyaJaiGanesh

(2)what's the command to rename a file?

int rename (const char *oldname, const char *newname)
The rename function renames the file oldname to newname. The file formerly accessible under the name oldname is afterwards accessible as newname instead. If rename fails, it returns -1.

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Re: Deleting a record from a file

Dec 16th, 2004

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(1)I have problem in deleting a record from a file.

Lets say you want to delete record 3 in a 10 record file:

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 C Syntax (Toggle Plain Text) 
int rec_to_delete = 2; // record 3 is index 2 
 
for(int i = 0; i < 9; i++)
{
    if(i != rec_to_delete)
    {
        // copy record
    }
}
int rec_to_delete = 2; // record 3 is index 2 

for(int i = 0; i < 9; i++)
{
    if(i != rec_to_delete)
    {
        // copy record
    }
}