CODEWITHSUNDEEP
c++binarycompressionfstream
YOTTA
YOTTA

Reputation: 1

How to read any kind of files as binary and edit it as you want (like compress it) with c++?

I'm trying to figure out a way to manipulate the binary code of any file in the computer in goal to apply a compress/decompress algorithm in c++ . I have been searching about that for long time and all i found was how to read a .bin file :

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

int main (){
streampos size;
char * memblock;

ifstream file ("name.bin", ios::in|ios::binary|ios::ate);
if (file.is_open())
{
size = file.tellg();
memblock = new char[size];
file.seekg (0, ios::beg);
file.read (memblock, size);

for(int i = 0 ; i < size ; i++){

    cout << memblock[i] ;

}

file.close();

cout << "\n\n the entire file content is in memory";

delete[] memblock;
}
else cout << "Unable to open file";
return 0;

}

I just wanna those bytes without ASCII translation, other words i wanna all the file as binary not what is inside it

Upvotes: 0

Views: 62

Answers (2)

YOTTA
YOTTA

Reputation: 1

The answer was simpler than we thought :

include bitset

for(int i = 0 ; i < size ; i++){

//changing the value of "memblock[i]" to binary byte per byte with for loop
//and of course using bitset

bitset<8> test (memblock[i]);
cout << test ;

}

Upvotes: 0

JohnFilleau
JohnFilleau

Reputation: 4288

<< is overloaded for char types to output the ASCII formated character. The data (the ones and zeros) in your memblock array are accurately read in as binary. It's just the way you're displaying them that is ASCII. Instead of a char[] for memblock, make it a uint8_t[]. Then, when you output, do

std::cout << std::hex << std::fill('0') << std::setw(2) << memblock[i];
             ^           ^                 ^
             |           |                 |
             |           |            sets the width of the next output
             |        sets the fill character (default is space)
          tells the stream to output all numbers in hexadecimal

You'll have to #include <iomanip> for the stream format manipulators hex, fill, and setw to work.

Note that setw will only be set on the stream for the next output operation, while hex and fill will be set until explicitly set otherwise. That said, you only need to set these two manipulators once, probably outside your loop. Then when you're finished, you can set them back like:

std::cout << std::dec << std::fill(' ');

See https://en.cppreference.com/w/cpp/io/basic_ostream/operator_ltlt2 for the list of overloaded operator<< functions for char and char arrays.

Upvotes: 2

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