In php, 0 == false, 0 == false will be equal, and false != false is the reason.

First look at a special case:

var_dump(0 == 'false'), returns bool(true), PHP determines that 0 is equal to any string;

var_dump(0==='false'), returns bool( false), the types and values ​​must be equal if they are congruent.
var_dump(0 == false), returns bool(true),

The reasons for the above results (translated from php official documentation):

1. For bool type:

When you output the bool type or When used in a statement, it will be converted into a number , true becomes 1, and false becomes 0.

For example, $a = true; var_dump($a+1), returns (int)2; $a is converted to 1, and the sum is 2;

A bool variable expresses a true value, and Rather than expressing a 0 or 1; Boolean types are not iconic constants, they have values.

2. String type:

php will always automatically try to convert strings into numbers. For example, var_dump('abc'+3'), returns int(3),

First 'abc' is converted into the number 0, and the addition becomes 3;

Method to detect the type of variable:
1. var_dump ($param) , will return the type and value of the variable.

2. Use is_int(), is_bool(), is_string(); functions to return true and false,

Integer type (int)$param

Character type (string)$param

Boolean type (bool)$param

Another way to convert to Boolean type: $a = !5, $a is false ,$a = !!5,$a is true;

The above introduces the reasons why 0 == false, 0 == false will be equal, and false ! = false in php. , including relevant content, I hope it will be helpful to friends who are interested in PHP tutorials.