Question

Below is something strange, I didn’t get

if (print("foo") || print("bar")) {
  // "foo" has been printed.
}

Why the output is 1?

Could please explain?

Answer 1

It’s because PHP is a ridiculous language. print is not a normal function, it’s a language construct. This line is actually parsed as:

if (print (("foo") || print("bar")))

And ("foo") || print("bar") is an expression which evaluates to 1. The string "foo" in a boolean context is true, so the || operator yields 1.

If you explicitly parenthesize the expression the way one would expect it to be parsed:

if ((print("foo")) || (print("bar"))) 

Then the output is what you would expect:

foo