Tukukkk

I want shift char array from read file and write output. but i got 2 errors. i dont know with this error.

1. no suitable conversion function from "std::valarray" to "const
   char *" exists




2. 'std::basic_ostream>
   &std::basic_ostream>::write(const _Elem
   *,std::streamsize)': cannot convert argument 1 from 'std::valarray' to 'const _Elem *'

void CaesarCipher(std::wstring i_inputFilePath, std::wstring o_outputFilePath, int shift)

{

    ifstream file(i_inputFilePath, ios::binary);

    if (file.is_open())

    {

        ofstream output(o_outputFilePath, ios::binary);

        std::array<char, 1024> buffer;

        while (!file.eof()) {

            file.read(buffer.data(), buffer.size());

            std::rotate(buffer.begin(), std::next(buffer.begin(), shift), buffer.end());

            output.write(buffer, buffer.size());

        }

        output.close();

        file.close();

    }

    else

    {

        cout << "File is not exist";

    }



}



int main()

{



    CaesarCipher(L"D:/input.exe", L"D:/output.exe", 1);

}

Your problem is with

output.write(dataShiftLeft, sizeof(data));

std::ostream::write takes a const char* and you provide a valarray<char>, that's why the compiler complains.

You need to iterate over the valarray and write the elements one by one:

for (auto c : dataShiftLeft) output << c;

But I'm confident that you would be better off with a std::array and the std::rotate algorithm, along those lines:

std::array<char, 1024> buffer;

// ...

file.read(buffer.data(), buffer.size());

auto trailing_zeros = std::rotate(buffer.begin(), std::next(buffer.begin(), 1), buffer.end()); // or 

std::fill(trailing_zeros, buffer.end(), 0);

With follow body of your CaesarCipher function should do the trick.

ifstream file(i_inputFilePath, ios::binary);

if (!file) {

    cout << "file is no existn";

    return;

}

std::array<char, 1024> buffer;

if (shift < 0) {

    shift = -shift;

    shift %= buffer.size();

    shift = buffer.size() - shift;

} else {

    shift %= buffer.size();

}

ofstream output(o_outputFilePath, std::ios_base::binary);

while (file.read(buffer.data(), buffer.size()) {

    std::rotate(begin(buffer), std::next(begin(buffer), shift), end(buffer));

    output.write(buffer.data(), buffer.size());

}

But I'd like to add that this does not look like a Caesar cipher function since you are to shift the individual characters within the defined alaphbet.