The difference between null,0,,false in PHP updatedata false javascript:false Async Fals

The empty () function is used to determine whether a string is empty

As long as the variable is 0,null, ", False,empty () is judged to be true.

    $num 1= ';    $num 2=0;    echo $num 1== $num 2;    Echo '
';    echo $num 1=== $num 2? ' 1 ': ' 0 ';

The result is:

The reason is that in PHP variables are stored in the structure of the C language, empty strings and null,false are stored with a value of 0, where the struct has a zend_uchartype, such a member variable, which is used to hold the type of the variable, and the type of the empty string is a string, The type of NULL is Null,false is Boolean. the = = = Operator Not only compares values, but also compares types.

Judging the empty string and 0 can do this:

    $num 1= ';    $num 2=0;    if (Empty ($num 1) && $num 1=== ") {    echo" true ";    }    if (Empty ($num 2) && $num 2===0) {    echo ' true ';    }

The result is:

The above describes the PHP null,0,,false differences, including the false,null aspects of the content, I hope the PHP tutorial interested in a friend helpful.

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