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❮ Php Import_Request_Variables Function Func Zip Entry Filesize ❯

PHP Type Comparison

Although PHP is a weakly typed language, it is also necessary to understand variable types and their meanings, as we often need to compare PHP variables, including loose and strict comparisons.

For example, "42" is a string while 42 is an integer. FALSE is a boolean value while "FALSE" is a string.

Example

<?php
if(42 == "42") {
    echo '1、Value is equal';
}

echo PHP_EOL; // Line break

if(42 === "42") {
    echo '2、Type is equal';
} else {
    echo '3、Type is not equal';
}
?>

The output of the above example is:

1、Value is equal
3、Type is not equal

Comparing 0, false, and null in PHP

Test code:

Example

<?php
echo '0 == false: ';
var_dump(0 == false);
echo '0 === false: ';
var_dump(0 === false);
echo PHP_EOL;
echo '0 == null: ';
var_dump(0 == null);
echo '0 === null: ';
var_dump(0 === null);
echo PHP_EOL;
echo 'false == null: ';
var_dump(false == null);
echo 'false === null: ';
var_dump(false === null);
echo PHP_EOL;
echo '"0" == false: ';
var_dump("0" == false);
echo '"0" === false: ';
var_dump("0" === false);
echo PHP_EOL;
echo '"0" == null: ';
var_dump("0" == null);
echo '"0" === null: ';
var_dump("0" === null);
echo PHP_EOL;
echo '"" == false: ';
var_dump("" == false);
echo '"" === false: ';
var_dump("" === false);
echo PHP_EOL;
echo '"" == null: ';
var_dump("" == null);
echo '"" === null: ';
var_dump("" === null);

The output of the above example is:

0 == false: bool(true)
0 === false: bool(false)

0 == null: bool(true)
0 === null: bool(false)

false == null: bool(true)
false === null: bool(false)

"0" == false: bool(true)
"0" === false: bool(false)

"0" == null: bool(false)
"0" === null: bool(false)

"" == false: bool(true)
"" === false: bool(false)

"" == null: bool(true)
"" === null: bool(false)
❮ Php Import_Request_Variables Function Func Zip Entry Filesize ❯