Program to copy its input to its output, replacing each tab by \t , each backspace by \b , and each backslash by \\

Question

I am trying to solve this K&R question. I tried this code in CodeBlocks.

int main()
{
    int c, d;
    while ( (c=getchar()) != EOF)
    {
        d = 0;
        if (c == '\\')
        {
            putchar('\\');
            putchar('\\');
            d = 1;
        }
        if (c == '\t')
        {
            putchar('\\');
            putchar('t');
            d = 1;
        }
        if (c == '\b')
        {
            putchar('\\');
            putchar('b');
            d = 1;
        }
        if (d == 0)
            putchar(c);
    }
    return 0;
}

But when i press backspace \\b is not being displayed in place of that.

Please help me.

Answer 1

It's because the console window handles keyboard and editing keys itself.

You have to look into the Windows console functions , especially the SetConsoleMode function.

---

To clear the ENABLE_PROCESSED_INPUT and ENABLE_LINE_INPUT flags:

// Get the console handle for `stdin`
HANDLE hConsoleStdin = GetStdHandle(STD_INPUT_HANDLE);

// Get the current flags
DWORD flags;
if (GetConsoleFlags(hConsoleStdin, &flags))
{
    // Now `flags` contain the current flags
    // Remove the flags we don't want there
    flags &= ~(ENABLE_PROCESSED_INPUT | ENABLE_LINE_INPUT);

    // And finally set the new flags
    SetConsoleFlags(hConsoleStdin, flags);
}

Note: The above code is not tested, as I don't have access to a Windows machine.

Answer 2

The problem actually is, your console does not pass the back-space to the program, but deletes the character from the input-buffer. As @JoachimPileborg said, see the use of SetConsoleMode and other functions.

Answer 3

这里回答了如何在Linux环境中完成此操作的详细信息。