Re: Saving a binary file into a string

Richard Herring <junk@[]>
Fri, 15 Jan 2010 14:02:22 +0000
In message
Rune Allnor <> writes

On 27 Des, 16:39, Dominik Schmidt <> wrote:


I'm new to C++, so I have a very basic question.
I wrote a function which opens a file and saves it into a string variable.
Another function can save a string variable into a file.
I tried to combine those two functions, because in combination they should
make an exact copy of a file. And it seems to work, in every case the copy
had the exact same hash value (MD5) as the original file.

I'd like to know if I made an error, so if there's any possibility that my
functions won't work in some case?

There is the possibility, yes.

Some byte values or sequences of byte values take on special
meanings like 'end of line' or 'end of string' in the context
of text files

Yes. But the OP is using binary files, so that's irrelevant.

and strings.

No. std::string can contain arbitrary sequences of characters without
any constraints on their values, and doesn't impose any semantics on

(The only potential problem is that '\0' is treated as a terminator when
assigning or constructing std::strings from C-style null-terminated
strings, i.e. when calling member functions or operators which take a
single const char * argument. The corresponding functions which take two
iterators (or pointers) don't share this problem.)

If you want to work with binary files, use std::vector<char>
or something like that, instead of std::string.

Probably good advice, since it makes the intent clearer, but not for the
stated reason:

That way all
characters are treated as arbitrary numbers, with no special
significance attached to any of them.

Richard Herring

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