Detect Ctrl + S in Console

Question

I'm developing a console application in which I need to detect several hotkeys such as Ctrl+N, Ctrl+O and Ctrl+S. Here's a part of the code that I use to recognize these hotkeys:

ConsoleKeyInfo input = Console.ReadKey(true);

if (input.Modifiers == ConsoleModifiers.Control)
{
    if (input.Key == ConsoleKey.N)
    {
        // ...
    }
    else if (input.Key == ConsoleKey.O)
    {
        // ...
    }
    else if (input.Key == ConsoleKey.S)
    {
        //...
    }
}

The code above works without any issues for Ctrl+N and Ctrl+O. But, I can't get it to work for Ctrl+S. After doing some quick testing, I found out that pressing Ctrl+S doesn't even do anything (meaning that the program is still waiting for the user to type something).

This issue only occurs with Ctrl+S. Using some simple if statements for any other modifier (Shift for example) and key (N, O, etc) works fine.

Why does this happen? Is there a special meaning to the Ctrl+S combination? Is it possible to make this work? If yes, how?

CTRL-S is caught by the console program to pause output. That's why it's not passed on to your application. I do not know how to disable it. — Some programmer dude, Sep 13 '16 at 17:54
I found this as well: http://stackoverflow.com/a/9951471/2524589 — KSib, Sep 13 '16 at 20:26

score 0 · Answer 1 · edited Feb 04 '17 at 08:26

0

protected override  bool  ProcessCmdKey(ref Message msg, Keys keyData)
{
    if (msg.Msg == 256)
    {
        //if the user pressed control + s
        if (keyData == (Keys.Control | Keys.S))
        {

        }
        //if the user pressed control + o 
        else if (keyData == (Keys.Control | Keys.O))
        {

        }
        //if the user pressed control + n 
        else if (keyData == (Keys.Control | Keys.N))
        {

        }
    }
    return base.ProcessCmdKey(ref msg, keyData);
}

edited Feb 04 '17 at 08:26

answered Feb 04 '17 at 07:54

GuyThehunter

1

1

How is this supposed to be called? Where does the `msg` and `keyData` come from? – William R. Oct 26 '19 at 14:34

score 0 · Answer 2 · answered Nov 05 '19 at 08:38

With help from ThreeStarProgrammer57, I came up with this solution for my own console application.

You need to configure the console by using SetConsoleMode and passing "ENABLE_WINDOW_INPUT | ENABLE_MOUSE_INPUT | ENABLE_EXTENDED_FLAGS as suggested by oconnor0".

Import the needed kernel functions:

[DllImport("kernel32.dll", SetLastError = true)]
static extern bool SetConsoleMode(IntPtr hConsoleHandle, uint dwMode);
[Flags]
private enum ConsoleInputModes : uint
{
    ENABLE_PROCESSED_INPUT = 0x0001,
    ENABLE_LINE_INPUT = 0x0002,
    ENABLE_ECHO_INPUT = 0x0004,
    ENABLE_WINDOW_INPUT = 0x0008,
    ENABLE_MOUSE_INPUT = 0x0010,
    ENABLE_INSERT_MODE = 0x0020,
    ENABLE_QUICK_EDIT_MODE = 0x0040,
    ENABLE_EXTENDED_FLAGS = 0x0080,
    ENABLE_AUTO_POSITION = 0x0100
}

[Flags]
private enum ConsoleOutputModes : uint
{
    ENABLE_PROCESSED_OUTPUT = 0x0001,
    ENABLE_WRAP_AT_EOL_OUTPUT = 0x0002,
    ENABLE_VIRTUAL_TERMINAL_PROCESSING = 0x0004,
    DISABLE_NEWLINE_AUTO_RETURN = 0x0008,
    ENABLE_LVB_GRID_WORLDWIDE = 0x0010
}

[DllImport("kernel32.dll", SetLastError = true)]
static extern IntPtr GetStdHandle(int nStdHandle);
static int STD_INPUT_HANDLE = -10;

And use them in your program as following:

// Add this section to your code:
SetConsoleMode(GetStdHandle(STD_INPUT_HANDLE), (uint)(
    ConsoleInputModes.ENABLE_WINDOW_INPUT |
    ConsoleInputModes.ENABLE_MOUSE_INPUT  |
    ConsoleInputModes.ENABLE_EXTENDED_FLAGS
));
// ------------------------------

ConsoleKeyInfo input = Console.ReadKey(true);

if (input.Modifiers == ConsoleModifiers.Control)
{
    if (input.Key == ConsoleKey.N)
    {
        // ...
    }
    else if (input.Key == ConsoleKey.O)
    {
        // ...
    }
    else if (input.Key == ConsoleKey.S)
    {
        //...
    }
}

This solution will not only allow you to capture Ctrl+S keystrokes, but also Ctrl+C!

Detect Ctrl + S in Console

2 Answers2

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