eval
(PHP 4, PHP 5)
eval — Evaluate a string as PHP code
설명
mixed eval
(
string $code
)
Caution
The eval() language construct is very dangerous
because it allows execution of arbitrary PHP code. Its use thus is
discouraged. If you have carefully verified that there is no other option
than to use this construct, pay special attention not to pass any user
provided data into it without properly validating it beforehand.
인수
-
code
-
Valid PHP code to be evaluated.
The code must not be wrapped in opening and closing
PHP tags, i.e.
'echo "Hi!";' must be passed instead of
'<?php echo "Hi!"; ?>'. It is still possible to leave and
re-enter PHP mode though using the appropriate PHP tags, e.g.
'echo "In PHP mode!"; ?>In HTML mode!<?php echo "Back in PHP mode!";'.
Apart from that the passed code must be valid PHP. This includes that all statements
must be properly terminated using a semicolon.
'echo "Hi!"' for example will cause a parse error, whereas
'echo "Hi!";' will work.
A return statement will immediately terminate the
evaluation of the code.
The code will be executed in the scope of the code calling eval(). Thus any
variables defined or changed in the eval() call will remain visible after
it terminates.
반환값
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().
예제
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";
?>
This is a $string with my $name in it.
This is a cup with my coffee in it.
주의
Note: 이것은 함수가 아닌
언어 구조이기 때문에, 가변
함수 방식으로 호출할 수 없습니다.
Tip어떠한 결과가 브라우저로 직접
출력될 때, 출력 제어 함수를
이용해서 이 함수의 출력을 캡쳐하여, (예를 들면) string으로
저장할 수 있습니다.
Note:
In case of a fatal error in the evaluated code, the whole script exits.