PHP Function eval of Introduction and Use Examples

2021-07-13 04:51:30
OfStack

What is eval ()?

The eval () function evaluates the string according to the PHP code.
The string must be a valid PHP code and must end with a semicolon.
If the return statement is not called in the code string, NULL is returned. If there is a parsing error in the code, the eval () function returns false.

Grammar

eval(phpcode)



 Parameter    Describe 

phpcode   Necessary. What is stipulated to be calculated  PHP  Code.

Example 1



<?php

$string = "beautiful";

$time = "winter";

 

$str = 'This is a $string $time morning!';

echo $str. "<br />";

 

eval("\$str = \"$str\";");

echo $str;

?>

Output:
This is a $string $time morning!
This is a beautiful winter morning!

Example 2

We use the for loop to create n casually, and the value is multiplied



<?php

 

for($i=1;$i<=10;$i++){

        eval('$a'.$i.'='.($i*$i).';');

}

 

for($i=1;$i<=10;$i++){

        eval('echo $a'.$i.'.\'<br />\' ;');

}

 

echo '<br />';

echo $a1 + $a10;

Output: