I am looking for the source and/or proper definition for the int() function. I have searched through the source in Arduino.app, without much success.

The reference gives a terse explanation

 x: a value of any type 
 Converts a value to the int data type

Passing 1, '1' or 49 returns the int 1. I haven't tested other types.

This seems to be an Arduino specific function - it doesn't seem to be in any c/c++ library.

1 Answer 1


int(x) is not a function but another way to perform an explicit cast of x to an int. It is part of the C++ language itself, that is why you could not find it in a library.

This is not Arduino-specific.

In C and C++ you can cast a value to an int by doing this:

int y = (int) x;

C++ has extended this notation by allowing to do it this way, which is equivalent:

int y = int(x);

You can find this in more details in C++ language reference.

  • to clear things i think add long x; above int y = int(x); in my opinion this would be better?
    – Martynas
    Jan 30, 2015 at 6:35
  • Thanks. I could not find this in any of my (admittedly old) c++ books, or in Xcode documentation.
    – Milliways
    Jan 30, 2015 at 6:41

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