Rogue characters on file write

[pmc]

Morning boys (and girls )

Bet you never thought you'd see me posting to this forum of coder's heaven, eh?

In an effort to do a bit of learning I've been converting my little software cipher to C++.

However, I've hit a bit of an issue. Everything works fine *except* I seem to get rogue characters tacked onto the end of the text that I write out to a file.

Here's the relevant loop in my code:

    ifstream inputFile(inFile, ios::in);

    if (!inputFile) {
    output_to_console(input_file_open_err_msg);
    return 0;}

    ofstream outputFile(outFile, ios::out);

    if (!outputFile) {
    output_to_console(output_file_open_err_msg);
    return 0;}

    while (!inputFile.eof()) {
    inputFile.get(in_char);

    out_char = perplexity_cipher(in_char);

    outputFile.put(out_char);
    if (!outputFile.good()) {
    output_to_console(output_file_write_err_msg);
    return 0;}
    }

    inputFile.close();
    outputFile.close();

any ideas what I'm doing wrong and why I get rogue characters at the end of an otherwise perfectly written text file?

[Leffmann]

I think what you're seeing is the automatic line ending conversion. Windows tries to be different and incompatible with everything else, and uses carriage return + line feed for line endings (byte sequence 13 and 10).

If you open your files in binary mode it should work:

// ios::in and ios::out are implied with ifstream and ofstream

ifstream inputFile(inFile, ios::binary);
ofstream outputFile(outFile, ios::binary);

and if you ever do C-style I/O then you would add "b" to the file mode:

FILE* f = fopen("i.bin", "rb");
FILE* f = fopen("o.bin", "wb");

[pmc]

No go I'm afraid

Same problem using binary mode rather than text mode

I changed the call to the cipher function so instead I just go:

    out_char = in_char;

And set my input text file to say: this is a test

what I get back is a text file saying: this is a testt

ie. The last actual character from the input file gets repeated and tacked on the end of the output file.

[pmc]

This fixes it:

    while (inputFile.good()) {
    inputFile.get(in_char);
    if (inputFile.eof()) {
    break;}

Massive thanks to CaptainHug/RSE - you're a legend mate!

[Leffmann]

Ok that was it I had no idea the EOF flag didn't update until after an I/O op. Keep the text mode in mind as well, it will both discard CR bytes as you read and insert new ones as you write. C++ streamed I/O is a real minefield.