in_array()

[asi]

I have wired code: PHP 8.1.2

if (in_array('false', [true], false)) {
    return true;
}

Above code return true ;/ why?

Above code is equivalent to:
 

if ('false' == true) {
   return true;
}

http://sandbox.onlinephpfunctions.com/code/6f6e1f06d145d74f71d2dc5fa08f36ef5dcda6ee

[Barand]

'false' is a string value, not a boolean false.

 

From the PHP manual...

Quote

When converting to bool, the following values are considered false:

• the boolean false itself
• the integer 0 (zero)
• the floats 0.0 and -0.0 (zero)
• the empty string, and the string "0"
• an array with zero elements
• the special type NULL (including unset variables)
• SimpleXML objects created from attributeless empty elements, i.e. elements which have neither children nor attributes.

Every other value is considered true (including any resource and NAN).