I have a very simple question, which happens to be hard for me since this is the first time I tried working with binary files, and I don't quite understand them. All I want to do is write an integer to a binary file.
Here is how I did it:
#include <fstream>
using namespace std;
int main () {
int num=162;
ofstream file ("file.bin", ios::binary);
file.write ((char *)&num, sizeof(num));
file.close ();
return 0;
}
Could you please tell me if I did something wrong, and what?
The part that is giving me trouble is line with file.write, I don't understand it.
Thank you in advance.
The part that is giving me trouble is line with file.write, I don't understand it.
If you read the documentation of ofstream.write()
method, you'll see that it requests two arguments:
a pointer to a block of data with the content to be written;
an integer value representing the size, in bytes, of this block .
This statement just gives these two pieces of information to ofstream.write()
:
file.write(reinterpret_cast<const char *>(&num), sizeof(num));
&num
is the address of the block of data (in this case just an integer variable), sizeof(num)
is the size of this block (eg 4 bytes on 32-bit platforms).
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