This article describes the boolean type in php in detail. if you need a friend, you can refer to it. I hope it will be helpful to everyone when converting to boolean, the following values are considered FALSE:
The Boolean value is FALSE.
The integer value 0 (0)
The floating point value is 0.0 (0)
Empty string and string "0"
Array that does not contain any elements
Objects that do not include any member variables (applicable only to PHP 4.0)
Special type NULL (including unset variables)
SimpleXML object generated from an XML document without any tags
All other values are considered to be TRUE (including any resources ).
Warning
-1 is considered TRUE like other non-zero values (both positive and negative values!
The code is as follows:
Var_dump (bool) ""); // bool (false)
Var_dump (bool) 1); // bool (true)
Var_dump (bool)-2); // bool (true)
Var_dump (bool) "foo"); // bool (true)
Var_dump (bool) 2.3e5); // bool (true)
Var_dump (bool) array (12); // bool (true)
Var_dump (bool) array (); // bool (false)
Var_dump (bool) "false"); // bool (true)
True => 1, false => "";