Check input redirection in CPP program

Question

We know how REDIRECTION unix shells behave as if the input from a file (eg: input.txt) comes from the keyboard.

So I am making a cpp program that can take input via CIN either with the keyboard or with a text file using redirection

eg: ./ a.out <input.txt

But how can I check in a C ++ program if the input entered was from a file or typed from the keyboard?

+3

Aditya sanghi 30 Aug 14 at 14:10

1 answer

John Zwinck · Accepted Answer · 2014-08-30T14:13:29+0000

This will tell you if stdin is a terminal:

isatty(STDIN_FILENO)