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(PHP 3, PHP 4, PHP 5)

eval -- Evaluate a string as PHP code


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.



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

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

Zwracane wartości

As of PHP 4, eval() returns NULL unless return is called in the evaluated code, in which case the value passed to return is returned. In case of a parse error in the evaluated code, eval() returns FALSE.

In PHP 3, eval() does not return a value.


Przykład 1. eval() example - simple text merge

= 'cup';
$name = 'coffee';
$str = 'This is a $string with my $name in it.';
$str. "\n";
"\$str = \"$str\";");
$str. "\n";

Powyższy przykład wyświetli:

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


Podpowiedź: Ze wszystkim, co wysyła dane bezpośrednio do przeglądarki, możesz używać funkcji kontroli wyjścia aby przejąć wyjście tej funkcji i zapisać je w zmiennej tekstowej (na przykład).

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

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