writing binary data (std::string) to an std::ofstream?

Question

I have an std::string object containing binary data which I need to write to a file. Can ofstream f("name"); f << s; be problematic in any way? I need to read the data back exactly as it was originally.

I can of course use fwrite(s.c_str(), s.size(), 1, filep), are there any pros / cons to either method?

Whilst what you're doing is perfectly valid (don't forget to open the ofstream in binary mode.. whether your data is binary or not, frankly) I would have used vector<char> for the added feel-good factor. Any reason you didn't? — Lightness Races in Orbit
– Lightness Races in Orbit, Commented Mar 18, 2011 at 16:51
@Tomalak: I am using a set of transformer classes that accept and return string. string seemed a convenient interface for manipulating buffers, like appending/substituting into another content etc. I though at one point to define a binaryString as basic_string<unsigned char>, but it required too much time for refactoring which I didn't have at that time. But could I use the << operator with vector<char>? — davka
– davka, Commented Mar 18, 2011 at 17:14
Nope. But then again I'd not want to use << for binary data anyway, as my brain reads it as "formatted output" which is not what you're doing. Again, it's perfectly valid, but I just would not confuse my brain like that. :) The native appending is certainly useful, though. — Lightness Races in Orbit
– Lightness Races in Orbit, Commented Mar 19, 2011 at 3:26
@TomalakGeret'kal et. al...may I draw your attention to this related question: stackoverflow.com/questions/8230786/… — HostileFork says dont trust SE
– HostileFork says dont trust SE, Commented Nov 23, 2011 at 11:39

Jon · Accepted Answer · 2011-03-18 16:48:28Z

7

You should be ok as long as you open the ofstream for binary access.

ofstream f("name", ios::binary | ios::out); 
f << s;

Don't forget to open your file in binary mode when reading the data back in as well.

answered Mar 18, 2011 at 16:48

Jon

3,0651 gold badge22 silver badges30 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

writing binary data (std::string) to an std::ofstream?

1 Answer 1

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related