CODEWITHSUNDEEP
c++windowsfilebinary
Boris Raznikov
Boris Raznikov

Reputation: 2453

Changing binary file

I have a file on windows. I'm writing in C++. I have a problem where I need to remove some bytes from the end of the file. I am using ifstream, but I don't know how to remove those chars, simple put '\0' in the file or what ?

Upvotes: 0

Views: 611

Answers (3)

A. K.
A. K.

Reputation: 38254

On linux machines, use truncate(): http://linux.die.net/man/2/truncate

On the Windows machines, use SetEndOfFile():

http://msdn.microsoft.com/en-us/library/aa365531%28v=vs.85%29.aspx

Both are OS dependent calls.

Upvotes: 2

James Kanze
James Kanze

Reputation: 154017

You can't portably change the size of a file; the only way to do it is to copy the file to a temporary, then delete the original and rename the temporary.

If it's just a case of truncating the file, both Windows and Unix (but not necessarily other systems) have system level functions which can do this, but there's nothing in the standard which supports it. And if you ever end up having to remove bytes other than at the end, neither Windows nor Unix allow it (although some other systems do, at least in specific cases).

Upvotes: 2

Nim
Nim

Reputation: 33645

Why not truncate the file? Have a look at the chsize() method.

Upvotes: 1

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