Compresssing Files using std::filesystem
Can I use std::filesystem
to compress files?
std::filesystem
does not provide built-in support for compressing files. It is designed primarily for file and directory manipulation, such as creating, deleting, moving, and copying files and directories. To compress files, you will need to use other libraries or APIs.
One popular library for compressing files in C++ is zlib
. It provides functions to compress and decompress data using the DEFLATE
compression algorithm. Here's a basic example demonstrating how to use zlib
to compress a file:
First, you need to include the zlib
library in your project. You can download it from zlib.net.
#include <zlib.h>
#include <filesystem>
#include <fstream>
#include <iostream>
namespace fs = std::filesystem;
void compress_file(
const fs::path &source,
const fs::path &destination) {
std::ifstream input(
source, std::ios_base::binary);
std::ofstream output(
destination, std::ios_base::binary);
if (!input || !output) {
std::cerr << "Failed to open file\n";
return;
}
constexpr int buffer_size = 128 * 1024;
char buffer[buffer_size];
z_stream zlib_stream;
zlib_stream.zalloc = Z_NULL;
zlib_stream.zfree = Z_NULL;
zlib_stream.opaque = Z_NULL;
zlib_stream.avail_in = 0;
zlib_stream.next_in = Z_NULL;
deflateInit(&zlib_stream, Z_DEFAULT_COMPRESSION);
int flush;
do {
input.read(buffer, buffer_size);
zlib_stream.avail_in = input.gcount();
flush = input.eof() ? Z_FINISH : Z_NO_FLUSH;
zlib_stream.next_in =
reinterpret_cast<unsigned char *>(buffer);
do {
char out_buffer[buffer_size];
zlib_stream.avail_out = buffer_size;
zlib_stream.next_out = reinterpret_cast<
unsigned char *>(out_buffer);
deflate(&zlib_stream, flush);
output.write(
out_buffer,
buffer_size - zlib_stream.avail_out
);
} while (zlib_stream.avail_out == 0);
} while (flush != Z_FINISH);
deflateEnd(&zlib_stream);
}
int main() {
fs::path source{R"(c:\test\hello.txt)"};
fs::path destination{R"(c:\test\hello.txt.gz)"};
compress_file(source, destination);
std::cout << "File compressed\n";
}
File compressed
In this example:
- We define
source
as the path to the file we want to compress anddestination
as the path to the compressed file. - We open the input file in binary mode and the output file in binary mode.
- We set up the
z_stream
structure forzlib
and initialize it withdeflateInit
. - We read chunks of data from the input file, compress them using
deflate
, and write the compressed data to the output file. - We use
Z_FINISH
to indicate the end of the input file and finalize the compression withdeflateEnd
.
This example demonstrates basic file compression using zlib
. For more advanced usage, including handling errors and different compression levels, refer to the zlib
documentation.
Alternatively, you can use other compression libraries like Boost.Iostreams
or libarchive
for more comprehensive file compression and decompression capabilities.
Working with the File System
Create, delete, move, and navigate through directories and files using the std::filesystem
library.