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:
source
as the path to the file we want to compress and destination
as the path to the compressed file.z_stream
structure for zlib
and initialize it with deflateInit
.deflate
, and write the compressed data to the output file.Z_FINISH
to indicate the end of the input file and finalize the compression with deflateEnd
.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.
Answers to questions are automatically generated and may not have been reviewed.
Create, delete, move, and navigate through directories and files using the standard library's filesystem
module.