How to insert a string at the beginning of the file?

suning0616

How to insert a string into a text file? Not covered!
Thank you!

orangedj

I'm stupid, I just read the original first, and then ...

lordkelvin

If the file size is hundreds of megabytes, isn't this method inefficient?

珈蓝易拉罐

But if you do n’t do that, would n’t the person writing the file system driver cry to her mother?

珈蓝易拉罐

Hehe, people who write file system drivers are not geniuses, they are also programmers like us, and we think they are very complicated. They are the same.
Imagine if you let you design a disk format and implement a set of file system drivers on it. To support random insertion and deletion without moving any data, of course, you must also consider disk utilization and read efficiency. (Especially efficient sequential read)-Do you think this is feasible? :)

lordkelvin

I haven't written a file system, those people are very good programmers for me :)

I think if the file is large, efficiency is really an issue. In order to insert a few characters, it may take several minutes or even longer.
I think things can be done better, so come up with this concern

珈蓝易拉罐

In some cases, people are really thinking of better ways, such as those for database systems.
But they are generally based on the same level of the file system and then encapsulate their own layer of a more abstract logical file format to achieve the purpose, such as dividing a file into pieces, putting a few bytes on each block header, and marking it. Is this piece still useful and where is the next piece?
But for ordinary occasions, this is not only tedious, but also not very beneficial in the matter, especially, you have to write, read, and assemble the program yourself, which is very troublesome.
If your file is a special binary file, it can be divided into fixed length records one by one, and if you are not afraid of trouble, you can also do this, hoho.
You can also consider using a B-tree, which is usually not necessary. :(

superandy

Fortunately, the landlord did not ask why the vector does not support push_front / pop_front.

stoneboy4000

The question from the landlord reminded me of viking virus,
Also insert a paragraph at the beginning of the exe file,
Generate a virus file and the original exe file when executed, and some bats, and execute, while inserting the beginning of other exe

Have the opportunity to ask the virus author ^ _ ^

珈蓝易拉罐

The exe seems to be a little better, sometimes there will be free bytes in front of it, and sometimes a jmp instruction can be inserted logically.