Keil Logo

_sys_istty()

4.43 _sys_istty()

Declared in rt_sys.h, the _sys_istty() function determines whether a file handle is attached to an interactive device.

Syntax

int _sys_istty(FILEHANDLE fh);

Usage

The ARM libraries call __sys_istty() to determine whether a file handle (that is being used for an output file stream) is attached to an interactive device.
For file streams that are attached to interactive devices, the ARM library:
  • Provides unbuffered behavior by default, in the absence of a call to setbuf() or setvbuf().
  • Prohibits seeking.

Restriction

stdin, stdout, and stderr, are interactive devices, but are line-buffered at program startup.

Returns

The return value is one of the following values:
0
fh is not attached to an interactive device.
1
fh is attached to an interactive device.
other
An error occurred.
Non-ConfidentialPDF file icon PDF versionARM DUI0378H
Copyright © 2007, 2008, 2011, 2012, 2014-2016 ARM. All rights reserved. 
  Arm logo
Important information

This site uses cookies to store information on your computer. By continuing to use our site, you consent to our cookies.

Change Settings

Privacy Policy Update

Arm’s Privacy Policy has been updated. By continuing to use our site, you consent to Arm’s Privacy Policy. Please review our Privacy Policy to learn more about our collection, use and transfers
of your data.