Read binary file and convert to binary string

Question

I am trying to write a function that reads specified number of bytes from a binary file and converts them into a string of 1's and 0's. What is the easiest way to do that. File is in BigEndian.

string ReadBytesFromFile(int size)
{
    string result;
    ifstream file ("example.bin", ios::in|ios::binary|ios::ate);
    if (file.is_open())
    {           
        memblock = new char [size];
        file.seekg (0, ios::beg);
        file.read (memblock, size);
        file.close();

        //need to convert memblock to binary string
        result = GetBinaryString(memblock);

        delete[] memblock;

    }
    return result;
}

Easiest way is probably using a bitset or itoa.

user142019
– user142019

2011-09-11 21:58:44 +00:00
Commented Sep 11, 2011 at 21:58 — user142019
– user142019, Commented Sep 11, 2011 at 21:58
Remember to unset the skipws flag.

K-ballo
– K-ballo

2011-09-11 21:59:03 +00:00
Commented Sep 11, 2011 at 21:59 — K-ballo
– K-ballo, Commented Sep 11, 2011 at 21:59

David Heffernan · Accepted Answer · 2011-09-11 21:58:21Z

2

Call itoa() passing 2 as the radix. Make sure you don't overrun your buffer!

Note: This isn't part of any C or C++ standard so be warned it is not portable. But you asked for ease rather than portability!

answered Sep 11, 2011 at 21:58

David Heffernan

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1 Comment

user142019 Over a year ago

Not part of the standard library, but I am sure there are open-source implementations of it which you can use if you want it to be portable.

Kleist · Accepted Answer · 2011-09-11 22:03:11Z

2

Take a byte at a time, and shift the bits off one by one.

Something like:

std::ostringstream ss;
for (int i=0; i<size; ++i) {
  char byte = memblock[i];
  for (int j=0; j<8; ++j) {
    ss << byte & 1;
    byte = byte << 1;    
  }
}

edited Sep 11, 2011 at 22:03

answered Sep 11, 2011 at 21:57

Kleist

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