What is the difference between "rb+" and "wb+"?

Question

rb+ and wb+ both read from and write to a binary file, so what makes them different?

Is it the order they read and write?

Solution

In short

• rb+ does not create the file from scratch

• wb+ does create the file from scratch

there are no differences aside that.

Comments

[Jon Clements]

Do you mean apart from the fact that opening in read only denies being able to write?

[user4815162342]

@JonClements Neither of these are read-only, + means "open a disk file for updating (reading and writing)".

[Jon Clements]

@user4815162342 ahh... yes... of course... that's quite an embarrassing brain burp of mine :)

[user4815162342]

It's important to realize that "create the file from scratch" implies "destroy (truncate to length 0) existing one, if found".

[Admin]

Oh so with rb+ the file must already exist?

[Zeromika]

@coder80 Indeed file must already exist while using rb+.

[user4815162342]

@coder80 Yes. Sadly, there is no mode for "use the file if it exists, create one if not". (Other than r and w, there is also x which is like the opposite of r, in that it will create the file if it doesn't exist, but it will fail if it exists.)