Urgent, help needed.

I was given an assignment to complete. I'm doing a library program which including borrow and return program. And here, i seek the advice on how to delete a line in a text file. My program work this way, when a student borrow a book, the studentid and the book code will be written in a file call relation.txt which contain 2 column ( studentid , bookcode), now what i want is the return program. When a student want to return a book, the program will ask for his studentid and the bookcode, and it will scan through the text file searching the number that match with the bookcode that being input by the student, after found it, it will delete that line in the text indicating the student already return the book. Do anyone has any idea how to write this program?

One way (more suitable for text format files), is to read in all the records that don't match the one you're looking for, and then write them out to a temporary file.

When you find the record you're looking for, just don't write that one out.

Continue writing out any remaining records in the text file, and close both files. Now delete the old file. Then rename the temporary file, with the original records file name.

Would it be easier to write a new file as Adak said or to alter the old file. ( in my mind, this is the way i thought of before, read the file, then strcmp the bookcode input by the student with the bookcode existed in the file and then delete the whole line.) Which program would be easier and less complicated?

There is no way to "delete" a line. The only way would be to move all the data below the line you want gone up, so it's a tad complex.
Adak's way is slower, but certainly more programmer friendly.

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