Header File 

io.h  

Category 

Input/output Routines 

Prototype 

int isatty(int handle); 

Description 

Checks for device type. 

isatty determines whether handle is associated with any one of the following character devices:

• a terminal
• a console
• a printer
• a serial port

If the device is one of the four character devices listed above, isatty returns a nonzero integer. If it is not such a device, isatty returns 0. 

Example  

#include <stdio.h>
#include <io.h>
int main(void)
{
    int handle;
    handle = fileno(stdout);
    if (isatty(handle))
       printf("Handle %d is a device type\n", handle);
    else
       printf("Handle %d isn't a device type\n", handle);
    return 0;
}

Portability