memory stream?

[andrew]

I am writing a program that involves reading in lots of (ASCII) data,
manipulating it, and then outputting some more. I am using ifstream and
ofstream.

Since I am reading a line, and writing a line at a time, my code can be
quite slow.

Is it possible, to use a memory stream, such that I read the entire
file in to memory first, and then can use it, just like a file stream?
Similarly, can I write to memory, just like I would be writing to a
file, and then write the entire data to disk?

Many thanks.

 

[Stefan Chrobot]

U¿ytkownik andrew napisa³:

> Is it possible, to use a memory stream, such that I read the entire
> file in to memory first, and then can use it, just like a file stream?
> Similarly, can I write to memory, just like I would be writing to a
> file, and then write the entire data to disk?
>
> Many thanks.
>

Yes, and it's easy. Just use stringstream. You can't construct
stringstream out of ifstream's buffer, but - as with all streams - you
can send the whole buffer to it.

#include <sstream>
#include <fstream>
using namespace std;

int main()
{
ifstream in("test.txt");
stringstream ss;
ss << in.rdbuf(); // Put the whole file into ss
// use ss as every other stream...
}

Stefan

 

[maxim.yegorushkin]

andrew wrote:

[]

Is it possible, to use a memory stream, such that I read the entire
file in to memory first, and then can use it, just like a file stream?
Similarly, can I write to memory, just like I would be writing to a
file, and then write the entire data to disk?

[]

You can't do it with std::stringstream. Alternatively, you can add
std:stream interface to an array.
http://groups-beta.google.com/group/comp.lang.c++.moderated/msg/a872eaedb142debc