大神们！求能把txt里的稿件以字为单位打乱的程序

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

#include <ctime>
#include <cstdlib>

int main(int argc, char** args)
{
    srand((unsigned int)time(NULL));
    for(int i = 1; i < argc; ++i)
    {
        std::vector<char> buffer;
        //reading
        {
            std::ifstream ifs(args[i]);
            std::istreambuf_iterator<char> eos;               // end-of-range or
            std::istreambuf_iterator<char> iit (ifs); // stdin iterator
            std::copy(iit, eos, std::back_inserter(buffer));
        }
        //shuffering
        std::random_shuffle(buffer.begin(), buffer.end());
        
        //output
        {
            std::ofstream ofs(args[i]);
            ofs.write(&buffer[0], buffer.size());
        }
    }
    return 0;
}