Format
#include <io.h> int isatty(int handle);
Language Level: XPG4, Extension
isatty determines whether the given handle is associated with a
character device (a keyboard, display, or printer or serial
port).
Note: In earlier releases of the C/C++ run-time library, isatty began with an underscore (_isatty). Because it is defined by the X/Open standard, the underscore has been removed. For compatibility, IBM C and C++ Compilers will map _isatty to isatty for you.
Return Value
isatty returns a nonzero value if the device is a
character device. Otherwise, the return value is 0.
Example
This example opens the console and determines if it is a
character device:
#include <io.h> #include <stdio.h> #include <stdlib.h>
int main(void)
{
int fh;
if (-1 == (fh = fileno(stdin))) {
perror("Error getting file handle from stdin.\n");
return EXIT_FAILURE;
}
if (0 != isatty(fh))
printf("stdin is a character device.\n");
else
printf("stdin is not a character device.\n");
return 0;
/***************************************************
The output should be:
stdin is a character device. ***************************************************/ }
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_inp -- Read Byte from Input Port
_inpd -- Read Doubleword from Input Port
_inpw -- Read Unsigned Short from Input
Port
_outp -- Write Byte to Output Port
_outpd -- Write Double Word to Output
Port
_outpw -- Write Word to Output Port
<io.h>