Write raw memory to file - c++

Question

I am trying to dump the memory (made with malloc) to a file. I want to dump the raw data because I don't know what's inside the memory (int float double) at the point that I want to dump the memory.
What's the best way to do this?
I have tried a few thing already but non of them worked as i wanted.

Answer 1

In C, it's quite trivial, really:
const size_t size = 4711;
void *data = malloc(size);
if(data != NULL)
{
FILE *out = fopen("memory.bin", "wb");
if(out != NULL)
{
size_t to_go = size;
while(to_go > 0)
{
const size_t wrote = fwrite(data, to_go, 1, out);
if(wrote == 0)
break;
to_go -= wrote;
}
fclose(out);
}
free(data);
}
The above attempts to properly loop fwrite() to handle short writes, that's where most of the complexity comes from.

Answer 2

It's not clear what you mean by "not working".
You could reinterpret_cast the memory to a char * and write it to file easily.
Reading it back again is a different matter.

Answer 3

The "C++ way" of doing it would probably involve using std::ostream::write with a stream in binary mode.
#include <fstream>
#include <string>
bool write_file_binary (std::string const & filename,
char const * data, size_t const bytes)
{
std::ofstream b_stream(filename.c_str(),
std::fstream::out | std::fstream::binary);
if (b_stream)
{
b_stream.write(data, bytes);
return (b_stream.good());
}
return false;
}
int main (void)
{
double * buffer = new double[100];
write_file_binary("test.bin",
reinterpret_cast<char const *>(buffer),
sizeof(double)*100);
delete[] buffer;
return 0;
}

Answer 4

If this is C++, this might help you, as part of serializing and deserializing,
I write the raw memory array to a file (using new[] is essentially the same
as malloc in the C world):
https://github.com/goblinhack/simple-c-plus-plus-serializer
#include "hexdump.h"
auto elems = 128;
static void serialize (std::ofstream out)
{
auto a = new char[elems];
for (auto i = 0; i > bits(a);
hexdump(a, elems);
}
Output:
128 bytes:
0000 00 01 02 03 04 05 06 07 08 09 0a 0b 0c 0d 0e 0f |................|
0010 10 11 12 13 14 15 16 17 18 19 1a 1b 1c 1d 1e 1f |................|
0020 20 21 22 23 24 25 26 27 28 29 2a 2b 2c 2d 2e 2f | !"#$%&'()*+,-./|
0030 30 31 32 33 34 35 36 37 38 39 3a 3b 3c 3d 3e 3f |0123456789:;?|
0040 40 41 42 43 44 45 46 47 48 49 4a 4b 4c 4d 4e 4f |#ABCDEFGHIJKLMNO|
0050 50 51 52 53 54 55 56 57 58 59 5a 5b 5c 5d 5e 5f |PQRSTUVWXYZ[\]^_|
0060 60 61 62 63 64 65 66 67 68 69 6a 6b 6c 6d 6e 6f |`abcdefghijklmno|
0070 70 71 72 73 74 75 76 77 78 79 7a 7b 7c 7d 7e 7f |pqrstuvwxyz{|}~.|