---
name: "onekey"
section: "3bobcat"
platform: "linux"
package: "libbobcat-dev"
version: "6.07.01-2"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/onekey"
---

# onekey(3bobcat)

Single keystroke input, not requiring \`Return’

## NAME

FBB::OneKey - Single keystroke input, not requiring \`Return’

## SYNOPSIS

**#include \<bobcat/onekey\>**\
 Linking option: *-lbobcat*

## DESCRIPTION

**OneKey** objects may be used to realize \`direct keyboard input’: a pressed key becomes available without the need for pressing *Enter*. The characters are obtained from the standard input stream. Direct key entry remains in effect for as long as the **OneKey** object exists. Once the object is destroyed the standard input stream will return to its default mode of operation, in which input is \`confirmed’ by a newline character.

## NAMESPACE

**FBB**\
 All constructors, members, operators and manipulators, mentioned in this man-page, are defined in the namespace **FBB**.

## INHERITS FROM

\-

## ENUMERATION

The **OneKey::Mode** enumeration is used to control echoing of returned characters. It has two values:

- o

  **OFF**: returned characters are *not* echoed to the standard output stream;

- o

  **ON**: returned characters *are* echoed to the standard output stream.

## CONSTRUCTORS

- o

  **OneKey(OneKey::Mode state = OneKey::OFF)**:\
   This constructor initializes the **OneKey** input object. By default, entered characters are not echoed. By constructing the object with the **OneKey::ON** argument, entered characters are echoed to the standard output stream.

-

  This construct throws an *Exception* exception if it not properly complete. The constructor may fail for the following reasons:

- o

  the standard input stream is not a tty (e.g., when the standard input stream is redirected to a file);

- o

  the current state of the standard input stream can’t be determined;

- o

  the standard input stream’s state can’t be changed to the \`direct keyboard input’ mode.

Copy and move constructors (and assignment operators) are not available.

## MEMBER FUNCTIONS

- o

  **int get() const**:\
   Returns the next character from the standard input stream, without the need for pressing *Enter*.

- o

  **void setEcho(OneKey::Mode state)**:\
   Changes the echo-state of the **OneKey** object. The argument may be either **OneKey::ON** or **OneKey::OFF**.

## EXAMPLE

```
/*
                              driver.cc
*/
#include <iostream>
#include <string>
#include <bobcat/onekey>
using namespace std;
using namespace FBB;
int main()
{
    try
    {
        OneKey onekey;
        cout << "Usage: 1: next chars are echoed, 0: no echo, q: quits\n";
        while (true)
        {
            char c;
            cout << "ready...\n";
            cout << "Got character ’" << (c = onekey.get()) << "’\n";
            switch (c)
            {
                case ’1’:
                    onekey.setEcho(OneKey::ON);
                break;
                case ’0’:
                    onekey.setEcho(OneKey::OFF);
                break;
                case ’q’:
                return 0;
            }
        }
    }
    catch (exception const &e)
    {
        cout << e.what() << endl;
        return 1;
    }
}
```

## FILES

*bobcat/onekey* - defines the class interface

## SEE ALSO

[**bobcat**(7)](/bobcat/7.md), [**tty**(3bobcat)](/tty/3bobcat.md)

## BUGS

None Reported.

## BOBCAT PROJECT FILES

- o

  *https://fbb-git.gitlab.io/bobcat/*: gitlab project page;

Debian Bobcat project files:

- o

  *libbobcat6*: debian package containing the shared library, changelog and copyright note;

- o

  *libbobcat-dev*: debian package containing the static library, headers, manual pages, and developer info;

## BOBCAT

Bobcat is an acronym of \`Brokken’s Own Base Classes And Templates’.

## COPYRIGHT

This is free software, distributed under the terms of the GNU General Public License (GPL).

## AUTHOR

Frank B. Brokken (**f.b.brokken@rug.nl**).