Misc. Функции
PHP Manual

eval

(PHP 4, PHP 5)

evalEvaluate a string as PHP code

Описание

mixed eval ( string $code_str )

Evaluates the string given in code_str as PHP code. Among other things, this can be useful for storing code in a database text field for later execution.

There are some factors to keep in mind when using eval(). Remember that the string passed must be valid PHP code, including things like terminating statements with a semicolon so the parser doesn't die on the line after the eval(), and properly escaping things in code_str . To mix HTML output and PHP code you can use a closing PHP tag to leave PHP mode.

Also remember that variables given values under eval() will retain these values in the main script afterwards.

Параметри

code_str

The code string to be evaluated. code_str does not have to contain PHP Opening tags.

A return statement will immediately terminate the evaluation of the string .

Връщани стойности

eval() returns NULL unless return is called in the evaluated code, in which case the value passed to return is returned. If there is a parse error in the evaluated code, eval() returns FALSE and execution of the following code continues normally. It is not possible to catch a parse error in eval() using set_error_handler().

Примери

Example #1 eval() example - simple text merge

<?php
$string 
'cup';
$name 'coffee';
$str 'This is a $string with my $name in it.';
echo 
$str"\n";
eval(
"\$str = \"$str\";");
echo 
$str"\n";
?>

Примерът по-горе ще изведе:

This is a $string with my $name in it.
This is a cup with my coffee in it.

Бележки

Забележка: Тъй като това е езикова конструкция а не функция, тя не може да бъде извикана посредством променливи функции

Съвет

Както за всичко, което изкарва данни направо в браузъра, функциите за управление на изхода могат да бъдат използвани за прихващане на изхода от тази функция и записването му като низ (например).

Забележка: In case of a fatal error in the evaluated code, the whole script exits.

Вж. също


Misc. Функции
PHP Manual