eval

eval

Evaluate a string as PHP code

mixed **eval** string $code

Evaluates the given as PHP. code

The code being evaluated inherits the

of the line on which the call occurs. Any variables available at that line will be available for reading and modification in the evaluated code. However, all functions and classes defined will be defined in the global namespace. In other words, the compiler considers the evaluated code as if it were a separate file. variable scopeevalincluded

Let op: > The language construct is because it allows execution of arbitrary PHP code. If you have carefully verified that there is no other option than to use this construct, pay special attention into it without properly validating it beforehand. eval*very dangerous**Its use thus is discouraged.*not to pass any user provided data

codeValid PHP code to be evaluated.

   The code must not be wrapped in opening and closing
   , i.e.
    must be passed instead of
   . It is still possible to leave and
   re-enter PHP mode though using the appropriate PHP tags, e.g.
   .
  PHP tags`'echo "Hi!";'``'<?php echo "Hi!"; ?>'``'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.
    for example will cause a parse error, whereas
    will work.
  `'echo "Hi!"'``'echo "Hi!";'`


   A  statement will immediately terminate the
   evaluation of the code. 
  `return`


   The code will be executed in the scope of the code calling . Thus any
   variables defined or changed in the  call will remain visible after
   it terminates.
  `eval``eval`




returns null unless 
is called in the evaluated code, in which case

the value passed to is returned. As of PHP 7, if there is a parse error in the evaluated code, throws a exception. Before PHP 7, in this case returned false and execution of the following code continued normally. It is not possible to catch a parse error in using . eval``return``return``eval``ParseError``eval``eval``set_error_handler

Voorbeeld: 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.

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

call_user_func