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_isatty

Determines whether a file descriptor is associated with a character device.

int _isatty( 
int fd  
);

fd

File descriptor that refers to the device to be tested.

_isatty returns a nonzero value if the descriptor is associated with a character device. Otherwise, _isatty returns 0.

The _isatty function determines whether fd is associated with a character device (a terminal, console, printer, or serial port).

This function validates the fd parameter. If fd is a bad file pointer, the invalid parameter handler is invoked, as described in Parameter Validation. If execution is allowed to continue, the function returns 0 and sets errno to EBADF.

Routine

Required header

_isatty

<io.h>

For more compatibility information, see Compatibility.

Libraries

All versions of the C run-time libraries.

// crt_isatty.c
/* This program checks to see whether
 * stdout has been redirected to a file.
 */

#include <stdio.h>
#include <io.h>

int main( void )
{
   if( _isatty( _fileno( stdout ) ) )
      printf( "stdout has not been redirected to a file\n" );
   else
      printf( "stdout has been redirected to a file\n");
}

stdout has not been redirected to a file
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