if I want to modify a record in a file and I don't know whether the record I'm looking for already exists can I do that in one pass without having to write out the whole file. e.g. This is the pseudo code
if value exists then
modify and print record to output file
print record to output file
rename output file back to original filename
If I do this and the value I'm searching for doesn't exist then I've re-written the entire contents of the original file needlessly. Hence is there anyway to redo the same loop so the first time round I see if the value exists and if it doesn't I don't bother creating an output file ?
So a redo for the whole loop rather than the current iteration of the loop ?