Question

I was looking to use OpenSSL to encrypt text in a file, and will need the text to be in an unsigned char array before I encrypt it. What is the easiest way read text from a file to an unsigned char array?

Answer 1

Your question is tagged both C and C++ _{(which isn’t constructive)}. I will give an answer for C++.

#include <fstream>
#include <iterator>
#include <vector>

using namespace std;

int main()
{
    ifstream in("filename.txt"); //open file
    in >> noskipws;  //we don't want to skip spaces        
    //initialize a vector with a pair of istream_iterators
    vector<unsigned char> v((istream_iterator<unsigned char>(in)), 
                            (istream_iterator<unsigned char>()));
    ...
}