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.
Parameters
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 .
Return Values
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().
Examples
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"; ?>
The above example will output:
This is a $string with my $name in it.
This is a cup with my coffee in it.
Notes
Note: Because this is a
language construct and not a function, it cannot be called using
variable functions
Tip
As with anything that outputs
its result directly to the browser, the output-control functions can be used to capture
the output of this function, and save it in a
string (for example).
Note:
In case of a fatal error in the evaluated code, the whole script exits.
See Also
call_user_func() - Call a user function given by the first parameter
